Media playback is unsupported on your device Media caption Steve Zimmer, LA Unified School District: "Do not send your children to school"

Los Angeles schools have been closed due to a threat emailed to the school district, two weeks after the deadly attacks in California.

The shutdown closed more than 1,000 schools attended by 640,000 students across the city and beyond.

A school district spokesman said the decision was made out of "an abundance of caution".

New York City officials said they received a similar threat but it was so "outlandish" they ignored it as a hoax.

Los Angeles Mayor Eric Garcetti said the FBI had confirmed it was not a credible threat. Schools will reopen Wednesday.

New York City Police Commissioner William Bratton accused his Los Angeles counterparts of overreacting.

But LA Police Chief Charlie Beck dismissed the criticism as "irresponsible".

"It is very easy in hindsight to criticise a decision based on results the decider could never have known,'' he said.

The threat came less than two weeks after 14 people were killed by a radicalised Muslim couple in San Bernardino, 60 miles (95km) east of Los Angeles.

"Earlier this morning we did receive an electronic threat that mentions the safety of our schools," said Steven Zipperman, chief of the Los Angeles school police department.

"We have chosen to close our schools today until we can be absolutely sure that our campuses are safe."

Image copyright AP Image caption Parents take their children home

Image copyright AP Image caption Police cordoned off premises to search

An unnamed police official told Associated Press news agency the email sent to New York City threatened an attack on "every school in the city" with pressure cooker bombs, nerve gas agents, machine pistols and machine guns.

In Los Angeles, the threatening email described an attack specific to the Los Angeles Unified School District with assault rifles and explosive devices, said Mr Beck.

In a reference to the San Bernardino tragedy, district superintendent Ramon Cortines said: "I think it's important to take this precaution based on what has happened recently and what has happened in the past."

Los Angeles Unified School District

second largest in the US

640,000 students, about 1,087 schools

district spans 720 sq miles (1,865 sq km)

includes Los Angeles and all or part of more than 30 smaller cities

Image copyright AP Image caption Police turned parents dropping off children away from schools

Officials notified parents to keep children at home or pick them up.

Lupita Vela, parent of an eight-year-old daughter who attends school in the district, told the AP news agency she was "terrified" getting the announcement, especially following the San Bernardino attacks.

She wants her daughter to feel safe at school, she said.

Another parent of a LAUSD student, Elinor McMillan, said she's a "nervous wreck".

In a separate incident, classes were also cancelled at San Bernardino Valley College on Tuesday due to a bomb threat made on Monday afternoon.

What's a credible threat?

FBI officials use the term "specific but non credible" when they have details about the location of the threat, such as a school or a house. But the officials can't say for sure that the person who made the threat is dangerous (and it's not a schoolboy prank).

"Specific means a very clear target," Frank Cilluffo, the director of George Washington University's homeland security policy institute, told me.

There are other cases when militants or criminals, known to them, make a threat, but they haven't said where the attack would take place.

That's when law-enforcement officials talk about a threat that is "credible but not specific".

Tara McKelvey, BBC White House reporter