{
  "id": "2016-03-24-mt-san-antonio-college-bomb-threat",
  "slug": "mt-san-antonio-college-bomb-threat-2016-03-24",
  "institution": {
    "name": "Mt. San Antonio College",
    "shortName": "Mt. SAC",
    "state": "CA",
    "type": "community-college",
    "alertSystemName": "Mt. SAC Alerts",
    "enrollment": 29000
  },
  "incident": {
    "date": "2016-03-24",
    "type": "bomb-threat",
    "cleryCategory": "emergency-notification",
    "headline": "Bomb threat with a stated detonation time evacuated campus; determined to be a hoax",
    "headlinePublic": "Bomb threat with a stated detonation time evacuated campus; determined to be a hoax",
    "summary": "On the morning of Thursday, March 24, 2016, [Mt. San Antonio College](https://abc7.com/walnut-high-school-mount-san-antonio-college-sac-mt/1261715/) (one of the largest community colleges in California) was [evacuated](https://www.nbclosangeles.com/news/local/Bomb-Threat-Forces-Evacuation-of-Mt-San-Antonio-College-373397781.html) and adjacent [Walnut High School was placed on lockdown](https://ktla.com/2016/03/24/two-walnut-area-schools-evacuated-amid-possible-bomb-threats-lasd/) after a bomb threat was received naming a 2:45 p.m. PDT detonation time. Los Angeles County Sheriff's deputies with bomb-sniffing dogs swept both campuses. The threat was determined to be a hoax: LASD tweeted at [1:22 p.m. PDT](https://archive.kpcc.org/news/2016/03/24/58885/mt-san-antonio-college-evacuated-walnut-high-on-lo/) that the threat had concluded and the Walnut High lockdown was lifted, and Mt. SAC tweeted at approximately [3:11 p.m. PDT](https://www.cbsnews.com/losangeles/news/unspecified-threat-prompts-evacuation-of-mt-sac-in-walnut/) that the campus was clear with classes resuming at 4:30 p.m. PDT. [18-year-old Adrian Mendoza of West Covina](https://www.nbclosangeles.com/news/18-year-old-man-arrested-in-connection-with-bomb-threat-at-mt-san-antonio-college/57305/), enrolled at both Walnut High School and Mt. SAC, was arrested on April 6, 2016 on suspicion of making a false report of a bomb or explosive device.",
    "outcome": "No device was found. The Walnut High School lockdown was lifted at 1:22 p.m. PDT after LASD tweeted the conclusion of the threat. Mt. SAC tweeted at approximately 3:11 p.m. PDT that the campus was clear, with classes scheduled to resume at 4:30 p.m. PDT. The threat was treated as a hoax; LASD bomb squad with K-9 units cleared both campuses well before the named 2:45 p.m. PDT detonation time. On April 6, 2016, 18-year-old Adrian Mendoza of West Covina, enrolled at both Walnut High School and Mt. SAC, was arrested on suspicion of making a false report of a bomb or explosive device.",
    "resolution": "confirmed-hoax",
    "casualties": {
      "killed": 0,
      "injured": 0
    }
  },
  "alerts": [
    {
      "sequence": 1,
      "type": "initial",
      "timestampApprox": "Approximately 10:30 a.m. PDT on March 24, 2016, shortly after the 10:24 a.m. PDT report",
      "channel": "sms",
      "verbatimText": "EMERGENCY ALERT: Report of threat to campus at 2:45pm. Calmly leave campus. Classes/services are closed until at least 4:30pm.",
      "isVerbatimConfirmed": true,
      "sourceUrl": "https://abc7.com/walnut-high-school-mount-san-antonio-college-sac-mt/1261002/",
      "sourceDescription": "ABC7 Los Angeles, quoting the Mt. SAC emergency alert text message sent to students",
      "annotations": [
        "The emergency alert text quoted the named threat time (2:45 p.m. PDT) directly to students, an unusual choice that gave the campus community a clear deadline to be away from buildings",
        "The alert directed students to 'calmly leave campus' rather than evacuate to a specific location, a less prescriptive approach reflecting Mt. SAC's commuter character",
        "Mt. SAC enrolls approximately 29,000 students and is one of California's largest community colleges; the named 4:30 p.m. PDT service-closure time created a structured operational window"
      ],
      "characterCount": 126
    },
    {
      "sequence": 2,
      "type": "update",
      "timestampApprox": "Late morning PDT on March 24, 2016",
      "channel": "email",
      "verbatimText": "",
      "isVerbatimConfirmed": false,
      "sourceDescription": "Reconstructed from CBS Los Angeles and Campus Times reporting on the Mt. SAC update",
      "annotations": []
    },
    {
      "sequence": 3,
      "type": "all-clear",
      "timestamp": "2016-03-24T15:11:00-07:00",
      "channel": "sms",
      "verbatimText": "",
      "isVerbatimConfirmed": false,
      "sourceUrl": "https://www.cbsnews.com/losangeles/news/unspecified-threat-prompts-evacuation-of-mt-sac-in-walnut/",
      "sourceDescription": "Reconstructed from CBS Los Angeles reporting on Mt. SAC's 3:11 p.m. PDT tweet declaring campus safe and resumption of classes at 4:30 p.m. PDT",
      "annotations": []
    }
  ],
  "context": "[Mt. San Antonio College](https://www.mtsac.edu/), known as Mt. SAC, is one of the largest community colleges in California, located in Walnut, eastern Los Angeles County. On the morning of [Thursday, March 24, 2016](https://abc7.com/walnut-high-school-mount-san-antonio-college-sac-mt/1261715/), at 10:24 a.m. PDT, Mt. SAC and adjacent [Walnut High School](https://ktla.com/2016/03/24/two-walnut-area-schools-evacuated-amid-possible-bomb-threats-lasd/) received a bomb threat that named a 2:45 p.m. PDT detonation time, an unusually specific time, which gave the Los Angeles County Sheriff's Department and Mt. SAC administrators a four-hour window to act. Mt. SAC was evacuated; Walnut High School, where students were minors who could not be released without parent pickup, was placed on lockdown. LASD deputies with [bomb-detection K-9 units](https://www.nbclosangeles.com/news/local/Bomb-Threat-Forces-Evacuation-of-Mt-San-Antonio-College-373397781.html) swept both campuses. At [approximately 1:22 p.m. PDT](https://archive.kpcc.org/news/2016/03/24/58885/mt-san-antonio-college-evacuated-walnut-high-on-lo/), LASD tweeted that the threat had concluded and the lockdown at Walnut High School had been lifted. Mt. SAC's separate all-clear came at [approximately 3:11 p.m. PDT](https://www.cbsnews.com/losangeles/news/unspecified-threat-prompts-evacuation-of-mt-sac-in-walnut/) (about 26 minutes after the named detonation time) and the college announced that classes would resume at 4:30 p.m. PDT. On April 6, 2016, [18-year-old Adrian Mendoza of West Covina](https://www.nbclosangeles.com/news/18-year-old-man-arrested-in-connection-with-bomb-threat-at-mt-san-antonio-college/57305/), enrolled at both Walnut High School and Mt. SAC, was arrested on suspicion of making a false report of a bomb or explosive device. The case is significant for the campus alert archive because it documents joint community-college and K-12 emergency-management coordination, a pattern recurring in California, where many community colleges sit immediately adjacent to high schools, and because the named-time bomb threat created an unusually structured decision window for administrators and law enforcement.",
  "keyFindings": [
    "The bomb threat named a specific detonation time (2:45 p.m. PDT) that gave administrators an unusually structured four-hour decision window",
    "Mt. SAC was evacuated while adjacent Walnut High School was placed on lockdown, different protocols reflecting K-12 vs community-college student-release rules",
    "LASD bomb-detection K-9 units swept both campuses, the standard Los Angeles County protocol for community-college bomb threats",
    "Walnut High School's lockdown was lifted at 1:22 p.m. PDT after LASD tweeted that the threat had concluded; Mt. SAC's separate all-clear was issued at approximately 3:11 p.m. PDT, with classes resuming at 4:30 p.m. PDT",
    "On April 6, 2016, 18-year-old Adrian Mendoza of West Covina, enrolled at both Walnut High School and Mt. SAC, was arrested on suspicion of making a false report of a bomb or explosive device"
  ],
  "responseTimeMinutes": 6,
  "sources": [
    {
      "title": "Bomb threat closes Mt. SAC College, prompts lockdown of Walnut High School (ABC7 Los Angeles)",
      "url": "https://abc7.com/walnut-high-school-mount-san-antonio-college-sac-mt/1261715/",
      "type": "local-media"
    },
    {
      "title": "Mount San Antonio College Evacuated Amid Possible Bomb Threat; Walnut High School on Lockdown (KTLA)",
      "url": "https://ktla.com/2016/03/24/two-walnut-area-schools-evacuated-amid-possible-bomb-threats-lasd/",
      "type": "local-media"
    },
    {
      "title": "All-Clear Given After Bomb Threat at Mt. San Antonio College (NBC Los Angeles)",
      "url": "https://www.nbclosangeles.com/news/local/Bomb-Threat-Forces-Evacuation-of-Mt-San-Antonio-College-373397781.html",
      "type": "local-media"
    },
    {
      "title": "Evening Classes To Resume At Mount San Antonio College In Walnut Following Threat (CBS Los Angeles)",
      "url": "https://www.cbsnews.com/losangeles/news/unspecified-threat-prompts-evacuation-of-mt-sac-in-walnut/",
      "type": "local-media"
    },
    {
      "title": "Mt. San Antonio College, Walnut High declared safe after bomb threat (89.3 KPCC)",
      "url": "https://archive.kpcc.org/news/2016/03/24/58885/mt-san-antonio-college-evacuated-walnut-high-on-lo/",
      "type": "local-media"
    },
    {
      "title": "Bomb threat closes Mt. SAC and Walnut High School (Campus Times)",
      "url": "https://lvcampustimes.org/2016/03/bomb-threat-closes-mt-sac-and-walnut-high-school/",
      "type": "student-newspaper"
    },
    {
      "title": "18-Year-Old Student Arrested in False Bomb Threat at Mt. San Antonio College (NBC Los Angeles)",
      "url": "https://www.nbclosangeles.com/news/18-year-old-man-arrested-in-connection-with-bomb-threat-at-mt-san-antonio-college/57305/",
      "type": "local-media"
    },
    {
      "title": "ABC7 Los Angeles, quoting the Mt. SAC emergency alert text message sent to students",
      "url": "https://abc7.com/walnut-high-school-mount-san-antonio-college-sac-mt/1261002/",
      "type": "local-media"
    }
  ],
  "confidence": "medium",
  "tags": [
    "bomb-threat",
    "community-college",
    "california",
    "walnut",
    "los-angeles-county",
    "k-12-coordination",
    "named-detonation-time",
    "evacuation",
    "lasd-bomb-squad",
    "k9-sweep"
  ],
  "dateAdded": "2026-05-03",
  "lastUpdated": "2026-05-03",
  "addedBy": "ingestion"
}