A 9/11 memorial in the San Diego-area community of Pacific Beach was vandalized on the 11th anniversary of the terrorist attacks.

The memorial sculpture, dedicated to first responders who died during the 2001 attacks, stands in front of a fire station and consists of two polished aluminum replicas of the World Trade Center towers. Engraved on the memorial are the names of the 430 police, firefighters and paramedics who died when the buildings collapsed after terrorists flew hi-jacked planes into them. Between the towers is a 250-pound section of a steel I-beam from the World Trade Center.

Firefighters told Fox 5 San Diego they heard the sound of the replica towers being knocked over at about 12:30 a.m. Tuesday morning. One of them said it sounded like someone had thrown a manhole cover.

"More than likely, this was intentional," San Diego Fire Capt. Bill Degrenier told Fox 5. "The crews on duty heard the tower go down. They gave chase, but the people got away."