The Los Angeles Unified School District said that schools will reopen on Wednesday, having earlier ordered its 640,000 students to stay home Tuesday after a bomb threat, officials of the nation's second-largest school system said.
New York City officials said they received the same bomb threat and concluded that it was a hoax, according to The Associated Press.
Los Angeles School Police said all students at district schools were sent home due to a possible electronic threat. KNBC reported that the email was sent late Monday.
"I decided to close schools, and this choice was not made lightly. It disrupted the lives of our students, our employees and their families. Based on recent events, I took this precaution out of an abundance of caution and to ensure safety and security in our schools," Superintendent Ramon Cortines told reporters at a press conference.
"Thanks to the extraordinary effort by Los Angeles Unified School Police and law-enforcement partners, all L.A. Unified schools and charters have been inspected and Chief Steven Zipperman has given the all-clear," he said. He added that the district will have crisis counselors available for students and employees who may need additional support.
Cortines had earlier said the threat was directed at "many schools, not specifically identified. ...That's the reason I took the action that I did."
Contrary to earlier reports, Los Angeles authorities did contact the FBI before deciding to shut schools, said Los Angeles Police Chief Charlie Beck.
Later in the day, several federal officials said the threat was most likely a hoax, according to Reuters.
NBC reported that the threat was emailed to a board member, resulting in the evacuation.
The email sent was from someone who claimed to be a Los Angeles high school senior who had been bullied and was going to attack the schools with guns, assault rifles and pistols, according to WNBC. The writer claimed to be a jihadist but used incorrect terminology, according to the report. New York police concluded it was a hoax because the threat they received had almost identical language, except that the writer claimed to be a student in New York.
New York Mayor Bill de Blasio said Tuesday morning he is "absolutely convinced" that there was no danger to schoolchildren in his city. New York Police Commissioner William Bratton said he thinks Los Angeles officials overreacted by deciding to close the nation's second-largest school system.
"I can tell you that we know of no other threats that we're aware of, unless other agencies have gotten specifics outside of LAUSD," said Steven Zipperman, chief of the LA School Police.
The district is the nation's second largest, enrolling more than 640,000 students in kindergarten through 12th grade, at over 900 schools, and 187 public charter schools.
"We need families and neighbors to work together with our schools and with our employees to make sure our kids are safe throughout the day," school board President Steve Zimmer said. "We need employers to show the flexibility that a situation like this demands. And we ask you to show the maximum possible flexibility with your employees who are primarily mothers and fathers and guardians today in this situation."
"This is a rare threat. We get threats all the time," Cortines had said earlier. "I think the circumstances in the neighboring San Bernardino, I think what has happened in the nation, I think what happened internationally. I, as superintendent, am not going to take the chance with the life of a student."
The Burbank Unified School District, Hawthorne public schools and Santa Monica-Malibu Unified School District remained open.
"It is very easy in hindsight to criticize the decision based on results the decider could never have known. It is also very easy to criticize the decision when you have no responsibility [for] the outcome of that decision," the LAPD's Beck said.
"In fairness, people are going to be pretty critical of the way the Los Angeles handled this, but let's remember it's two weeks since the San Bernardino shooting. I think that at the moment they are particularly sensitive to the threat," said Frances Townsend, former Homeland Security advisor to President George W. Bush.
— CNBC's Ritika Shah contributed to this report.