The Los Angeles school district says hundreds of schools closed yesterday after an email threat would reopen today.
The nation's two biggest school systems - New York City and Los Angeles - received threats yesterday of a large-scale jihadi attack with guns and bombs, and LA reacted by shutting down the entire district, while New York dismissed the warning as an amateurish hoax and held classes as usual.
Read More:
• LA terror threat: 1000 schools closed but New York dismisses threat as a hoax
• California shooting: What you need to know
• California mass shooting: Police name slain suspects
The shutdown was a rare example of a major US city closing its entire school district because of fears of an attack.
The decision also reflected lingering unease in the aftermath of the shooting that killed 14 people at an office holiday party two weeks ago in nearby San Bernardino. In LA, the threat came in the form of an email to a school board member.
Authorities in New York reported receiving the same "generic" 360-word email and decided there was no danger to schoolchildren. Mayor Bill de Blasio concluded the threat contained "nothing credible". He added: "It was so outlandish."
The shutdown abruptly closed more than 900 public schools and 187 charter schools attended by 640,000 students across Los Angeles. LA officials defended the move, with that city's police chief dismissing the criticism as irresponsible.
Police Chief Charlie Beck said: "It is very easy in hindsight to criticise a decision based on results the decider could never have known."