The lockdown is lifted at Potomac High School in Oxon Hill after police said a person was trespassing on school grounds.

The school was placed on lockdown as a precaution Tuesday morning, Prince George's County Police tweeted.

Police say a former student, the trespasser, met with a current student on school grounds. The SRO questioned the current student and during that process a gun was recovered.

A current Potomac High student was taken into custody by police. But police continue to look for the other student, an 11th grader who transferred last year to Croom High School in Cheltenham.

Police continue to investigate the situation. The lockdown was lifted at 11:40 a.m.