BOYNTON BEACH, Fla. (AP) — Florida authorities arrested two teenagers Friday for making shooting threats against two separate schools, days after the mass bloodshed in Parkland.

The cases are the latest among dozens of threats involving students who express to other classmates or on social media networks that they plan to shoot up schools, officials said.

A national organization that tracks school threats says it has recorded about 50 a day on average since 17 people were killed in the mass shooting at Marjory Stoneman Douglas High School, compared with about 10 a day on average.

The Boynton Beach police spokeswoman Stephanie Slater said that a 14-year-old boy told two other students in a Facetime video call that he was going to attack SouthTech Preparatory Academy. In the chat, the student showed what appeared to be two different firearms.

Officers placed the school and a nearby preschool on lockdown while they tried to locate the student on Friday. But detectives found him inside a home, arrested him and recovered an air rifle and air pistol. No actual weapons were found, but the teen was charged with disrupting a school function.

Separately, the Clay County Sheriff's Office says it arrested a 13-year-old girl in a Jacksonville suburb for making threats through social media to attack a junior high school. The student faces two felony charges. The sheriff's office says it had already made another arrest in the same suburb since the Feb. 14 attack in Parkland.

Sheriff Darryl Daniels said in a press conference late Friday that the Oakleaf Junior High School student tried to cover her tracks and reported the post, but deputies traced it back to her.

"It's not cute, children, to make these types of posts. There's more serious things going on," Daniels said. "Knock that crap off."

The Ohio-based Educators School Safety Network says school threats are on the rise nationwide since the Florida shooting, including dozens on social media, about 10 incidents where a gun was brought to school and 22 bomb threats. The organization has tracked more than 350 school-based threats from Feb. 15 to last Thursday.