The SFPD bomb squad examines a box found on the beach below Fort Funston Sunday. Photo: Mike Demers

The San Francisco Police Department exploded what was believed to be a box of military flares on the beach below Fort Funston on Sunday.

“A visitor found a box of what looked like flares on the beach below the Fort Funston hang glider deck,” said Golden Gate National Recreation Area spokesman George Durgerian. “They were marked ‘U.S. Navy.’”

The visitor reported the find to National Park Service rangers at about 10:45 a.m. Sunday, Durgerian said.

Rangers closed off the fort and contacted the San Francisco Police Department’s bomb squad, which blew up the box on the beach. The bomb squad and rangers cleared the popular park area just south of Ocean Beach by about 1:10 p.m., according to Durgerian.

GGNRA Director of Communications Howard Levitt said it’s not uncommon for visitors to find unexploded ordnance or other devices, relics of the fort’s past as a part of the national coastal defense system.

“This was an active military post and people do find remnants of that activity,” he said.

However, Levitt added that the box found Sunday was “apparently not” from the same era as most of the devices found there, and could have been something that recently fell from a naval vessel.

Durgerian said that Fort Funston had been shut down earlier this week when someone found a different piece of unexploded ordnance there.