LOS ANGELES: Los Angeles shut down the United States' second-largest public school system on Tuesday after officials received a threatening email mentioning backpacks and packages, two weeks after a married couple inspired by Islamic State killed 14 people in San Bernardino just 100 km away. The unprecedented move left some 643,000 students of the Los Angeles Unified School District and their families scrambling to make alternate arrangements and drew criticism as officials in New York said they received the same threat and deemed it not to be credible.

A law enforcement source told Reuters that Los Angeles authorities ordered the closure to allow a full search of about 900 public school facilities without consulting with the Federal Bureau of Investigation, which takes the lead on any potential terrorism investigation. But the city's mayor, Eric Garcetti, denied that assertion, saying that officials had contacted federal law enforcement officials. Los Angeles Police Chief Charlie Beck said at a news conference that he was contacted late Monday night about a "very specific threat" delivered by email to school board members. Some other public schools in the city remained open as did private schools.

The Los Angeles school district regularly receives threats, but this one stood out for its scale, schools Superintendent Ramon Cortines said. "This is a rare threat ... It was not to one school, two schools or three schools, it was many schools," Cortines told reporters. A US official said investigators were looking for a possible bomb or bombs in connection with the Los Angeles closure. The threat came via an email sent to a school board member and mentioned backpacks and other packages, Cortines said.

New York City Police Commissioner William Bratton said that city's school system, the largest in the United States, had received "almost exactly the same" threat yesterday but deemed it non-credible. "LA is a huge school system," said Bratton, who had served as police chief in Los Angeles. "To disrupt the daily schedules of half a million school children, their parents, daycare, buses based on an anonymous email, without consultation, if in fact, consultation did not occur with law enforcement authorities, I think it was a significant over reaction."

Los Angeles Mayor Garcetti defended the closure. "It is very easy for people to jump to conclusions and I have been around long enough to know that usually what people think in the first few hours is not what plays out in later hours," Garcetti told a press conference. "But decisions have to be made in a matter of minutes."

Police Chief Beck said it was "irresponsible" to criticize the decision to close the schools in the aftermath of the Dec 2 attack on a regional center in San Bernardino, California, east of Los Angeles. The attack and other mass shootings have pushed the issues of militant Islamism and gun violence to the forefront of the US presidential campaign.

'You Hope it's a Hoax'

Students already at school were sent home, officials said, and families scrambled to come up with plans after the last-minute closures. "It's disappointing," said Trinity Williams, a high school student who dropped off her younger sister at elementary school, only to find it was closed. The two traveled on to Williams' high school before they realized the whole system was shut down. "I was supposed to give an essay in class today, and finals are Friday," Williams said. "I can't afford to miss a day."

Lee Stein, a parent with a daughter in fifth grade at Ivanhoe Elementary School, said he heard about the closure via a news alert to his phone, which he confirmed by calling the principal. "It's very concerning, especially in light of recent events," Stein said. "You hope it's a hoax. It's unfortunate that someone is preying upon people's fears." Other parents used social media to vent frustration at having learned about the closures from the news media, rather than directly from the schools. Ronna Bronstein, who has two sons in the fifth and eighth grades, said she was trying to find out more about the threat while shielding her younger child from the news. "I don't want him to be frightened to go back to school tomorrow," she said.

School officials said that on Sept 11, 2001, when many people returned home early from work after the attacks on the East Coast, Los Angeles schools remained open. The United States has suffered repeated deadly attacks in schools in recent years, typically carried out by gunmen. The deadliest one in the past decade occurred at Virginia Tech, where a shooter killed 32 people. In the second deadliest, a lone gunman shot dead 20 young children and six educators at Sandy Hook Elementary School in Newtown, Connecticut, in 2012. - Reuters