The combination of Mayan calendar doomsday predictions, last week’s mass killing at a Connecticut school, and widespread (though unsubstantiated) predictions of violence on social media has led to this:

Friday is a day when some parents, in South Florida and across the nation, are simply too scared to send their kids to school.

“There’s no information to lead us to believe that there’s a credible threat,” Chief of Broward Schools Police David Golt insisted Thursday.

Said Miami-Dade Schools spokesman John Schuster: “We anticipate a regular day of learning.”

Those reassurances aren’t enough for parents like Jeff Dillard, who won’t be sending his son to West Broward High School in Pembroke Pines on Friday. Dillard said he’s generally been impressed with the level of security at Broward public schools — and security has been at heightened levels all week — but that didn’t matter this time.

“We are choosing to keep our son at home,” Dillard said. “Just as a precaution, it’s better to be safe than sorry.”

Schools in three Michigan counties went so far as to cancel classes on Thursday and Friday, at least in part due to fears of violence. That action — along with media headlines that “armored backpacks” are suddenly a hot-selling child-protection item — signaled that America’s sense of safety is still reeling after a lone gunman killed six adults and 20 children last week at Connecticut’s Sandy Hook Elementary School.

On social media sites such as Twitter and Facebook, rumors have persistently suggested something ominous was about to happen at various schools. Miami-Dade Police this week arrested a 16-year-old student at Miami Lakes Educational Center who threatened on Twitter “to shoot up this school,” but other than that one incident, there has been no proof that any local schools are actually in danger.

In the case of the one teen who was arrested, no weapons were found.

Davie police, meanwhile, have spent days investigating rumors of imminent danger at Western High School. The department came up dry.

“We have nothing,” said Davie Police Capt. Dale Engle. “It’s an unconfirmed rumor is really what it boils down to.”

Even though police found no cause for alarm, students at Western were told to leave their backpacks at home on Thursday and Friday. Broward School District spokeswoman Tracy Clark said principals historically have sometimes banned backpacks on the days before winter break (students have a tendency to cause more mischief on those days) but Clark acknowledged that last week’s school tragedy “has the country on edge.”

“There is a heightened sense of awareness due to the incidents in Connecticut,” Clark said.

The end of a portion of the Mayan calendar on Friday — which some have interpreted as predicting the end of the world — might also be contributing to the general sense of anxiety. But CNN reported Thursday that many Mexicans of Mayan descent aren’t worried at all, and NASA even made a point to post on its website that “nothing unusual” was expected in the days ahead.

The social media rumors surrounding local schools, said Golt, the Broward Schools police chief, are similar to that old game of Telephone: one person whispers something in one person’s ear, which is passed along to another person, and so on.

The end result is a whole lot of misinformation.

Diana Reeves Tejada, president of the PTSA for Palmetto High School in Pinecrest, said she’s been fielding about 20 calls a day from parents worried about sending their children to school. Over and over, she’s told them to calm down.

“Rumors are just that, rumors,” said Tejada, who added that her daughter will be going to school on Friday.