A British sailor aboard a nuclear-powered submarine apparently shot dead a crew member and seriously wounded another Friday while the vessel was on a goodwill visit to an English port, officials said.
The suspect was overpowered by colleagues and visiting dignitaries aboard HMS Astute and arrested on suspicion of murder.
Police and military officials said the incident was not related to terrorism, but offered few details about what may have prompted a sailor to open fire during a tour of the submarine by local officials, including the mayor of Southampton, in southern England.
Britain's Press Association news agency reported the dead and injured crewmen were officers, and the suspect a sentry armed with an SA80 service rifle. Submariners do not routinely carry loaded firearms aboard ships, but those on sentry duty are armed.
Southampton city council leader Royston Smith said he was in the submarine's control room when a man entered, said something, then retreated to a corridor. Two shots rang out before the man walked back in and opened fire.
"I decided the best form of defense at that point was probably to disarm the chap," Smith told the BBC.
Smith said he and others managed to wrestle the gun away from the suspect and subdue him.
Hampshire Police Chief Superintendent David Thomas said only that a gun went off aboard the submarine, "which resulted in two crew members being injured."
"One of these injuries proved fatal. A man, also a member of the Royal Navy, was arrested at the scene on suspicion of murder," Thomas said. "Submarine security was not breached as part of this incident and it is not terrorist-related."
He said the wounded sailor's injuries were "significant," but his condition was stable.
The Defense Ministry said it would not release the names of the dead and injured until their families had been informed.
Defense Secretary Liam Fox said he was saddened by the "tragic incident."
Police said they were called to the shooting just after 12 p.m. (1100 GMT, 7:00 a.m. EDT). They said all of the approximately 30 people aboard the submarine at the time would be interviewed as witnesses.
The submarine, which is based in Scotland, was on a five-day visit to Southampton.
The 1 billion pound ($1.6 billion) vessel is one of Britain's fleet of 11 nuclear-powered submarines, armed with Spearfish torpedoes and Tomahawk cruise missiles. Its reactor is designed to last for the vessel's 25-year operational life, meaning it will never need to be refueled.
The 328-foot-long (100-meter-long) submarine's short career has been dogged by problems. Originally, due to enter service in 2005, it began active duty in 2010, years behind schedule and millions of dollars over budget.
In October, the Astute hit rocks and ran aground near the Isle of Skye off the west coast of Scotland. It was stuck for several hours until it was towed to safety. The vessel's commander was later removed from his post.
The Defense Ministry said it planned to open a Royal Navy investigation into Friday's shooting.