FORT LUPTON, Colo. -- Three Fort Lupton schools were placed on lockdown Tuesday morning after a small-caliber gun was found in a bathroom on the high school campus.

The lockdown was precautionary, and lifted by 2 p.m., police said.

Police don't know yet who brought the gun to school but investigators are following several leads, said Donald E. Grannis, Fort Lupton's police chief. Investigators are reviewing security cameras that captured people coming and leaving the area in the morning.

"We took this very seriously as the safety of our kids is paramount. I was very pleased with the response of the school staff and administration. The lockdown went according to the training we have conducted with the school staff," Grannis said.

Fort Lupton police received a call from high school authorities at 9:55 a.m. that a gun had been found on school grounds. Minutes later, the high school was placed in lockdown. Fort Lupton Middle School and Butler Elementary, both of which are across the street from the high school, were also locked down.

Officers secured the perimeter and searched the premises but no other weapons were found.