The investigation into LAUSD threat is still ongoing. Preliminary assessment is it was a hoax to disrupt school districts in large cities.

? Adam Schiff (@RepAdamSchiff) December 15Mission accomplished, then.

Meanwhile, Rep. Brad Sherman has given the most detailed account of the threat. In various interviews, Sherman has said that the writer of the email claimed to be a devout Muslim who had been bullied when he attended an L.A. Unified high school. The writer claimed to have 32 jihadist friends who were ready to attack various schools with rifles, bombs and nerve gas.

New York Police Commissioner Bill Bratton said the threat appeared to resemble a plot from the TV show Homeland, according to ABC News.

The closure of all 900 L.A. Unified school sites has forced parents to skip work and disrupted the lives of millions of people.

The mayor's office tweeted that LACMA and the Petersen Museum would be free to L.A. Unified students. LACMA later clarified that it is always free for children under 18. (Parents and guardians still have to pay though.)

11:31 a.m.:

Los Angeles officials are defending the decision to shut down the 900-plus schools in LAUSD after an email was sent out threatening a terrorist attack.

LAPD Chief Charlie Beck said at a press conference, I think it's irresponsible, based on facts that have yet to be determined, to criticize that decision. All of us make tough choices. All of us have the same goal in mind, to keep the kids safe.

LAUSD Superintendent Ramon Cortines had said earlier, I think it's important to take this precaution based on what has happened recently and what has happened in the past.

Cortines, by the way, is only the interim superintendent and is all but out the door. As L.A. Times reporter Howard Blume tweeted on Friday night, emails sent to Cortines are answered by an automatic response, directing all inquiries to Deputy Superintendent Michelle King, who happens to be applying for Cortines' job.

According to the L.A. Times, a 17-year-old boy was killed crossing a street in Highland Park when a city service truck killed him.

9:33 a.m.:

Police are searching more than 900 L.A. Unified campuses after a credible threat was emailed to a board member from overseas, according to KTLA. School is closed for the day for some 700,000 students.

The email was reportedly traced to Frankfurt, Germany, and included mention of backpacks and other packages at multiple school sites.

The New York school system received a similar threat, but is treating it as a hoax. Schools there are open.

It's very important not to overreact in situations like this, said New York Mayor Bill de Blasio, at a news conference. New York Police Commissioner William Bratton said the email appeared to be a hoax in part because Allah was not capitalized.

In a statement, L.A. Mayor Eric Garcetti said that L.A. Unified students can get home on MTA buses for free today.

We will continue to monitor this situation, he said. Nothing is more important to me than the safety of our families.

8:05 a.m.:

City News Service and FOX News are reporting that all Los Angeles Unified School District schools will?stay closed today in response to a reported bomb threat, Schools Superintendent Ramon Cortines said, a bizarre, dark and possibly historic event.

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The apparent bomb threat, of which no details were released, was allegedly called in to one of the city's seven elected LAUSD?School Board members.

That means more than 800 schools, and some 600,000-plus children, including those at charter schools, will all be hunkered down today, one of the busiest school weeks as children and teachers prepare to finish up, turn in assignments and complete tests before the Christmas break.

Cortines, a temporary superintendent who hopes to step down soon amidst a troubled search for a replacement superintendent, described the situation as ``a rare threat,'' City News Service reported after a hastily called news conference.

He has?ordered all campuses searched before the end of the day today, a daunting and probably chaotic task.

Cortines said he ordered the closures because he was not going to take a?chance given recent terror strikes in Paris and San Bernardino.

Board of Education President Steve Zimmer, the news service reported, said the district was acting``out of an abundance of caution.''