At least five people have been killed and a suspect found dead after Britain's worst mass shooting in over a decade took place in Plymouth, southwest England, police have said. Police said officers and ambulance staff were called to respond to a "serious firearms incident" in Biddick Drive, in the Keyham area of the seaside city of Plymouth, around 6:10 p.m. local time. Two women and two men were found dead at the scene, according to police. Another woman was treated for gunshot wounds at the scene and died a short time later in hospital. Another man, believed to be the offender, was also found dead. All are believed to have died from gunshot wounds. Police have stressed that this was not a terrorism-related incident. They added that the area has been cordoned off and that the situation is believed to be contained. Luke Pollard, a member of parliament for Plymouth Sutton and Devonport, tweeted that more people are being treated in hospital for injuries and that at least one of those killed was a child. Mass shootings are exceedingly rare in the United Kingdom. A massacre at a Scottish school in 1996 prompted the country's government to tighten gun laws and ban private gun ownership, and Thursday's incident is the deadliest of its kind since 2010, when a shooting spree in Cumbria, northern England, claimed 12 lives. Prime Minister Boris Johnson said his "thoughts are with the friends and family of those who lost their lives and with all those affected by the tragic incident in Plymouth last night." "Just so unspeakably awful. My condolences and thoughts are with the families," Pollard added on Twitter. "I'm utterly devastated that one of the people killed in the #keyham shooting was a child under ten years old." Lawmaker Johnny Mercer added that the incident was "serious and tragic" and described Thursday as a "truly devastating day." Police appealed to the public to not "speculate or share pictures of the scene on social media or anywhere else."