One person was killed and a second suffered life-threatening injuries in a shooting on board a Royal Navy nuclear-powered submarine today, police in Britain said today.
Officers arrested a man after the incident on HMS Astute, which is currently docked in Southampton.
Hampshire Police said the incident was not terror-related and there was no risk to the public.
Police and the Ministry of Defence would not comment on reports that the person who died in the shooting was a Royal Navy officer.
Hampshire Police said in a statement: "In both cases next of kin have not been notified, but officers are in the process of informing the families.
"No further details about the injured people will be released until this has been done."
HMS Astute, the British Navy's newest and most advanced submarine, was docked at Southampton's Eastern Docks on a five-day official visit to the city.
Police were alerted to the shooting by the Ministry of Defence at 12.12pm today.
"We believe two people have sustained injuries as a result of gunshots which have been discharged aboard the vessel," police said in a statement.
Armed police, firefighters, paramedics and the Hampshire and Isle of Wight Air Ambulance helicopter were sent to the dockside where the submarine was berthed.
HMS Astute previously hit the headlines when it ran aground on a shingle bank between the Scottish mainland and the Isle of Skye and remained marooned for several hours.
The embarrassing incident in October last year cost Commander Andy Coles his command of the submarine. He was replaced by Commander Iain Breckenridge.
HMS Astute was named and launched by the Duchess of Cornwall in June 2007 before being welcomed into the Royal Navy in August last year at a commissioning ceremony at Faslane Naval Base on the Clyde.
The submarine weighs 7,800 tonnes, equivalent to nearly 1,000 double-decker buses, and is almost 100 metres long.
Its Spearfish torpedoes and Tomahawk cruise missiles are capable of delivering pinpoint strikes from 2,000km (1,240 miles) with conventional weapons.
The submarine's nuclear reactor means that it will not need refuelling once in its entire 25-year life and it makes its own air and water, enabling it to circumnavigate the globe without needing to surface.
Built by defence giant BAE Systems at Barrow-in-Furness, Cumbria, it was the first in a fleet of six which will replace the Trafalgar class submarine.