Groton — A sailor assigned to the attack submarine USS San Juan was found dead early Thursday morning in a locked space on a barge housing crewmembers while their submarine is undergoing maintenance.

The sailor's death is being investigated. His name is not being released at this time. The Navy says foul play is not suspected.

"Our thoughts are with the sailor's family, friends and the crew of the USS San Juan," Chief Monique Meeks, a spokeswoman for the waterfront at the Naval Submarine Base, said Friday.

The San Juan, a Los Angeles-class attack submarine, is undergoing routine maintenance in drydock at the Naval Submarine Base. Adjacent to the submarine are two barges — a berthing barge and a working barge.