Two teens were arrested Thursday for threatening to shoot up their Brooklyn high school, police sources said.

The unidentified students at Brooklyn Prospect Charter School in Windsor Terrace, both 16, posted the threats on Snapchat at around 4 p.m. Wednesday, according to the sources.

“Don’t come to school tomorrow,” they said in one of the messages.

“We gunning you down tomorrow,” they said in another.

A third teen who doesn’t attend the school posed with a gun in the online post, the sources said.

Administrators at the school were alerted to the threat and contacted police, who then got in touch with the students’ parents.

One of the teens was picked up at his home Thursday morning and taken to the 72nd Precinct, while the other turned himself in.

A BB gun was found at one of the teen’s homes, sources said.

Both suspects were awaiting charges at the 72nd Precinct, according to sources.

“The parents were very concerned. One parent instructed me to tell her child to go straight home after school,” an English teacher at the high school told The Post.

“The teachers were very shocked and disappointed. We’re such a small school and a close-knit community with a lot of freedom. So this was completely unexpected.”