All schools in the Los Angeles Unified School District were shut down today following an unspecified threat, the Los Angeles Police Department said, as New York City deemed a similar threat not credible.

The Los Angeles closings are out of “an abundance of caution," the LAPD said. A senior law enforcement official told ABC News the threat was not serious and the LAPD is not on tactical alert. The threat is not connected to any previous threats or the San Bernardino investigation, the official said.

An electronic threat was received in Los Angeles this morning mentioning the safety of the schools, officials said at a news conference today.

The threat was emailed from outside the country and named a number of specific schools, according to two law enforcement officials briefed on the investigation. The last IP address linked to the email threat came from Frankfurt, Germany, according to an LAUSD official.

The threat involved many schools, L.A. Unified School District Superintendent Ramon Cortines said today. The threat "was to students at school" and mentioned backpacks and "other packages," Cortines said. The threat wasn't made to school buses, he added.

The email threatened violence to students, L.A. Mayor Eric Garcetti said.

“The email was very specific to L.A. Unified school district campuses and it included all of them,” LAPD Chief Charlie Beck said. “The implied threat was explosive devices. The specific threat was attack with assault rifles and machine pistols.

“These obviously are things that we take very seriously,” Beck added. “We worked with the FBI to vet this as best as possible.”

Officials are still vetting whether the threat was credible, Beck added.


PHOTO: Parents take their children home from school early, Dec. 15, 2015, in Los Angeles.Ringo H.W. Chiu/AP Photo
Parents take their children home from school early, Dec. 15, 2015, in Los Angeles.


PHOTO: A vehicle leaves the Miguel Contreras Learning Complex past a sign that reads No School Go Home, Dec. 15, 2015, in Los Angeles.Ringo H.W. Chiu/AP Photo
A vehicle leaves the Miguel Contreras Learning Complex past a sign that reads "No School Go Home," Dec. 15, 2015, in Los Angeles.more +

Meanwhile, a similar threat was reported in New York City. The New York Police Department tweeted today there "was a specific but NON credible threat made to NYC schools this morning," but nothing was closed.

A police source told ABC News the threat to New York City schools was received via email around 5 a.m. and was similar in nature to the threat made to Los Angeles schools. The police in New York deemed it not a credible threat, the source said.

New York’s mayor and police commissioner said today the wording of the threat suggested it was a hoax and the intelligence division of the NYPD decided there was nothing credible. Schools in New York, unlike Los Angeles, are under mayoral control.

The email originated overseas, New York Police Commissioner Bill Bratton said, adding that the language indicated it was not from a credible source.

New York City Mayor Bill De Blasio called the threat “outlandish" and generic, saying it would have been a "huge disservice” to close the schools.

Schools Chancellor Carmen Farina said, “We are working closely with the NYPD and there is no reason for alarm. As always, the safety of our students and staff both in and around schools is our number one concern and any extra needed security measures will be taken.”


PHOTO: A lock holds the gate shut at Edward Roybal High School in Los Angeles, Dec. 15, 2015.Richard Vogel/AP Photo
A lock holds the gate shut at Edward Roybal High School in Los Angeles, Dec. 15, 2015.

In Los Angeles, all LAUSD schools will be searched by the end of the day, officials said.