One submarine crewmember has died and a second suffered life-threatening injuries in a shooting on board HMS Astute in Southampton.
Hampshire Police arrested a Royal Navy serviceman after the incident on the nuclear-powered sub, which hit the headlines last year when it ran aground off the Scottish coast.
Southampton City Council said the local authority’s mayor, leader and chief executive were on board the Astute at the time of the shooting but were not injured.
A Ministry of Defence spokesman said: “Two Royal Navy personnel have been involved in a firearms incident at Southampton docks where HMS Astute is alongside.
“Sadly, one has now died as a result of his injuries. The Royal Navy is now attempting to inform their families as a matter of urgency.
“A third Royal Navy serviceman has been arrested by Hampshire Constabulary and is now in custody.
“This incident was not terrorist-related and there is no threat to the wider public. We are co-operating fully with the police investigation and a Royal Navy service investigation will begin in due course.
“All concerned family members should call the MOD’s Joint Casualty and Compassionate Centre on 0845 7800 900.”
Defence Secretary Dr Liam Fox said: “I am greatly saddened to hear of this incident and of the death of a Royal Navy service person in this tragic incident. It is right and proper that a full police investigation is carried out and allowed to take its course. My thoughts and sympathies are with those who have been affected and their families.”
A Hampshire Police spokesman said no further details about the victims until their families had been informed.