A Copiague Middle School student was arrested Monday for making a threat of mass harm on social media, Suffolk County police say.

Officers responded to the school at around 6:45 a.m. following a 911 call from school officials.

A 12-year-old boy posted a photo on Instagram that showed a gun, police say.

Tyjia Carpenter, of Copiague, says his daughter goes to Copiague Middle School and says they first were told students had a delayed opening.

"She called me this morning and she's like, 'We can't go to school! There's a threat at the school,'" he said. "We went by there. Security was outside. The cops was there. It was serious man."

It was determined that the threat was not credible following an investigation.

The student has been charged with making a threat of mass harm. He will be arraigned at a later day.

Elijah Curtis, of Copiague, says he can’t believe something like that would happen in a typically quiet hamlet.

"This is a calm community, too. A lot of crazy stuff doesn't usually happen over here, so hearing something like that is very surprising,” he said.

The middle school will remain closed Tuesday for a regularly scheduled professional development day.