SHIRLEY >> Authorities say a state prison was temporarily put on lockdown after a gunshot was heard outside and a man was seen running away.

State police say corrections officers heard the shot around 3:30 p.m. at the Massachusetts Correctional Institution in Shirley. A man wearing dark pants was seen fleeing.

The prison was locked down while the area was searched by troopers, police dogs and a helicopter with an infrared camera. The man was not found and the search ended several hours later.

The prison is located about 40 miles northwest of Boston and houses medium and minimum security inmates.