After receiving word that all Los Angeles schools would shut down Tuesday because of a threat of possible attack, many parents' first thoughts were about how to discuss the scary situation with their kids.

Lupita Vela's 8-year-old daughter enjoys attending Eagle Rock Elementary on the city's northeast side, and Vela was worried about her daughter feeling unsafe in class.

"I don't want this to be in the back of her head," she said. "Who knows what it does psychologically to kids? Is this going to cause her some kind of trauma so that she's not going to feel safe at school?"

The shutdown at the nation's second-largest district abruptly closed more than 900 public schools and 187 charter schools attended by 640,000 students across the Los Angeles area.

New York City officials said they got the same threat but quickly determined it was not credible. Hours later, the ranking Democrat on the House Intelligence Committee said it was believed to be a hoax.

Los Angeles police say the emailed threat was specific to all the campuses in the vast district and included implied threats about explosive devices, assault rifles and machine pistols.

Parents should first reassure themselves by getting as much information as possible about potential risks, according to Dr. Jason Hershberger, chair of psychiatry at Brookdale University Hospital in New York. Then sit down with the child and find out his or her specific fears, he said.

"Each kid has a different relationship with school, with teachers, with other kids in class. So their fears can be very unique," Hershberger said. "Ask them, 'What is the thing you're most afraid of?'"

It's important to emphasize to children that while there are dangers in the world, there are also plenty of ways to deal with them and stay safe.

"There are police, there are teachers, there are parents. When bad things happen, good people get together and figure out how to face it," Hershberger suggested telling frightened children.

The decision to close the Los Angeles district disrupted the morning routines of many families who found themselves suddenly facing discussions about fears rather than what cereal to eat.

Bobby Kim, co-founder of LA streetwear brand "The Hundreds," was making breakfast for his children when they learned of the closure.

"It's a strange thing to have to explain to your kids, but I guess that's the world we live in," Kim said.

Vela, who also has a son who is a high school senior, called the threat "absolutely terrifying" in light of the San Bernardino attack, which killed 14 people earlier this month. She got an automated phone call informing her of the closure.

"I know the kids are anxious," she said. "Of course they're texting all their friends. Their phones are blowing up."

Communication between kids and their friends is important, and parents should resist the urge to shield young people from scary news, said Dr. Karen Rogers, a child psychiatrist at Children's Hospital Los Angeles.

She suggested comparing the shutdown to preparations for earthquakes — a practice familiar to every California schoolchild.

"Earthquakes are a risk, but they don't happen very often," Rogers said. "A threat like this is no different. It's about being prepared, taking precautions."

Many parents were supportive of school officials' better-safe-than-sorry approach.

Kim said he was "appreciative for the prompt response and closures" but he hoped the "heightened terrorism climate" wouldn't become a major worry for his kids.

Lucrecia Santibanez, whose son attends a Los Angeles school, agreed.

"The one thing I'm afraid of is now anyone can call in with a hoax and send everyone scrambling for options for their children," she said.