Authorities say a high school in northeast Philadelphia is on lockdown after a school security officer reported a weapon missing from his car.

Police say the Kensington Urban Education Academy was placed on lockdown as a precaution just before 10:30 a.m. Tuesday after the missing weapon was reported.

Authorities say the officer told them he doesn't know exactly when the off-duty weapon disappeared.

The school serves grades 9 through 12 and reported enrollment of 353 during the 2015-2016 school year.