All Los Angeles Unified School District schools were closed Tuesday morning until further notice after LAUSD received a “credible threat,” according to school district officials.

District superintendent Ramon Cortines explained the "message" referred to backpacks and "other packages." He said many schools were threatened, though none by name. The threat was toward students in schools (as opposed to on buses), reported CNN

Cortines added: "The circumstances in the neighboring San Bernardino, I think what has happened in the nation, I think what happened internationally" played into the decision. "I, as superintendent, am not going to take the chance with the life of students."

The superintendent said he's asked authorities to search all of the roughly 900 charter and K-12 schools in his district "before the day is over." He promised that schools won't open until, he said, "I know it's safe."

However, former Los Angeles police chief Bill Bratton is criticizing the closing of the schools, said New York City officials said Tuesday morning they received the same threat but quickly concluded that it was a hoax, the Associated Press reported.

"Bratton said the person who wrote the note claimed to be a jihadist but made errors that made it clear the person was a prankster. Bratton said one indication that the email is a hoax is that Allah was not spelled with a capital “A”, the Associated Press reported.

“The language in the email would lead us to believe that this is not a jihadist initiative,” he said. “That would be incredible to think that any jihadist would not spell Allah with a capital ‘A’.”

Mayor Bill de Blasio said that he was “absolutely convinced” there was no danger to schoolchildren in New York. “An everyday hoax is something that has to be weighed smartly, but I have tremendous faith in the….NYPD leadership that they assess these type of realities all the time,” de Blasio said.

Speaking on KNX 1070 NEWSRADIO, LA Mayor Eric Garcetti defended the move and said the threat was taken seriously in light of the recent San Bernardino attack. “I think if you noticed in San Bernardino, it is always a mistake to assume we know everything early on, to say it’s an underreaction or an overreaction or it is just this or it is a hoax or it’s real, that is what is being vetted by our law enforcement partners,” said Garcetti.

The mayor also noted the specificity of the threat. “The knowledge of people’s email addresses, some particular things that were said that targeted LAUSD, so it was specific,” said Garcetti. “I am not going to second-guess that right now, we are going to support what is happening on the ground.”

Read more: