Los Angeles public schools will reopen on Wednesday after an emailed threat caused officials to cancel classes on Tuesday.

Authorities haven't given details of the threat but school Superintendent Ramon Cortines said the text referred to "backpacks, talked about other packages."

School Board President Steve Zimmer said at a news conference Tuesday evening that teams from numerous law enforcement agencies had searched 1,531 school properties and decided that it is safe to reopen. Mayor Eric Garcetti said the FBI has determined the threat is not credible.

Rep. Adam Schiff, the ranking member of the House Permanent Select Committee on Intelligence, said earlier Tuesday that "the preliminary assessment is that it was a hoax or something designed to disrupt school districts in large cities." Both Los Angeles and New York schools got the emails.

At the evening news conference, Garcetti resisted the use of the word hoax, suggesting instead "criminal mischief," or someone testing the vulnerabilities of cities.

State school superintendent Tom Torlakson noted that the closure and the investigation were costly and "somebody needs to pay for that."

Law enforcement officials have told NPR that the email sender — the source of the "electronic threat" — wrote that he had attended Los Angeles schools and had been bullied.

New York City officials decided not to close schools over their version of the email Tuesday morning. Police Commissioner William Bratton said it was not a credible terrorist threat and he was "concerned with people overreacting to it." Mayor Bill DeBlasio called the threat "outlandish."

Garcetti said New York officials did not see their email until Tuesday morning, and had the advantage at that point of knowing that it was not the only threat against U.S. public school systems when they made the decision to hold classes as normal.

Officials said that when the Los Angeles schools reopen, there will be extra law enforcement patrols, and that officers who normally wear civilian clothes will be in uniform to help reduce children's anxiety.

The Los Angeles metro area is still reeling from a terrorist attack in San Bernardino that left 14 people dead.

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