A Newtown Middle School teacher was found with a concealed gun at the Connecticut school Wednesday morning and has been arrested and placed on administrative leave, according to police.

Police officers responded to the school at 11 Queen St. around 9 a.m. after school staff called and said security staff were detaining a teacher who was seen in the school carrying a firearm, police said. The school is in the same town as Sandy Hook Elementary, where a deadly mass shooting in 2012 prompted strict gun laws statewide.

Police identified the teacher as Jason M. Adams, 46, of Newtown, and said he was found with a concealed firearm.

“We really don’t know the motive and why he was carrying it in school," Chief James Viadero with the Newtown Police said.

After he was detained briefly, police charged Adams with possession of a weapon on school grounds.

He was released on his own recognizance and is due in court in Danbury on April 20. It wasn't immediately clear if he had an attorney.

"This matter is very serious and troubling, both the Newtown Public School system and the Newtown Police Department took immediate steps to address the matter," the Newtown School System said in a statement that police released. "The teacher was immediately detained by security personnel. The teacher has additionally been placed on administrative leave pending an administrative investigation. Both agencies have been working closely together to investigate the incident and are taking precautions to ensure the continued safety of our students, staff and community members."

The state of Connecticut enacted some of the strictest gun laws in the nation after the December 2012 shooting at Sandy Hook Elementary School in Newtown, where 20 first graders and six educators were killed.

One parent described Adams as "kind, helpful, considerate."

“I’m shocked," Liz O'Connell, a student's parent, told NBC Connecticut. "I think it’s horrible, obviously I don’t know the reason why but it was a stupid mistake."

Adams has a valid State of Connecticut pistol permit, according to police. They have contacted the State's Licensing and Permit Unit and made them aware of the arrest.

Police said school policy strictly forbids the possession of firearms on school property.

Dan Corcoran contributed to this report.