Several people have died at the scene of a "serious firearms incident" on Thursday in Plymouth, southwest England, according to a police statement.
The incident is not being treated as terror-related, a local representative said on Twitter.
In a statement, Devon and Cornwall Police said: "Police were called to a serious firearms incident in Biddick Drive, in the Keyham area of Plymouth at around 6.10 pm today (local time)".
"Officers and ambulance staff attended," police said.
"There have been a number of fatalities at the scene and several other casualties are receiving treatment.
"A critical incident has been declared."
The police added that the area has been cordoned off and that the situation is believed to be contained.
Police also appealed to the public to not "speculate or share pictures of the scene on social media or anywhere else."
Johnny Mercer, a Member of Parliament (MP) for Plymouth Moor View, said in a tweet that the incident is "not terror-related," and that the suspect is not on the run.
Plymouth Sutton and Devonport PM Luke Pollard said in an earlier message on Twitter that "this looks like a very grim day for our city and our community".
Gun-related homicides are rare in the UK.
A mass shooting in 1996 prompted the UK to tighten the country's gun laws and ban private gun ownership.