Kittery, Maine — A Groton-based submarine already severely damaged in a fire last month was threatened Saturday evening by a small fire outside the ship that was quickly extinguished.

By the time the Portsmouth Naval Shipyard Fire Department arrived, a shipyard spokesperson said, the small blaze outside of the USS Miami had already been put out by a shipyard employee.

The 7:13 p.m. blaze in Dry Dock No. 2 never endangered the ship's reactor, and no radioactive material was involved, Deb White, the public affairs officer, said. The cause remains under investigation.

The Miami (SSN 755) was in a dry dock at the Portsmouth Naval Shipyard for maintenance and upgrades when a fire started in a vacuum cleaner at 5:41 p.m. May 23. The fire on board burned until 3:30 a.m. the next day and caused an estimated $440 million in damages to the Groton-based sub.

Officials have yet to decide whether to repair or scrap the submarine, which had been at the shipyard since March undergoing 20 months of maintenance.