There have been a "number of fatalities" following what British police have described as a serious firearms incident in the southwestern city of Plymouth this evening.

Police were called to the incident at Biddick Drive, in the Keyham area of Plymouth at around 6.10pm.

Emergency services attended the scene, where "several other casualties" are receiving treatment.

"A critical incident has been declared. The area has been cordoned off and police believe the situation is contained," Devon and Cornwall police said in a statement.

"Road closures are in place so please avoid the area."

"We are appealing to the public not to speculate or share pictures of the scene on social media or anywhere else."

Earlier, the South Western Ambulance Service said it was called at just after 6pm to an "ongoing incident" in Keyham.

"We responded to the incident with a significant number of resources, including Hazardous Area Response Teams (HART), multiple ambulances, air ambulances, multiple doctors and senior paramedics," it said on social media.

"We will provide an update here in due course."

British Home Secretary Home Secretary Priti Patel said: "The incident in Plymouth is shocking and my thoughts are with those affected. I have spoken to the Chief Constable and offered my full support.

"I urge everyone to remain calm, follow police advice and allow our emergency services to get on with their jobs."

Local MP Johnny Mercer said the "serious and tragic" incident in Plymouth is "not terror related".

The suspect involved is not "on the run" Mr Mercer said, urging the public to remain calm.

Local Labour MP Luke Pollard tweeted: "Really worrying news coming out of Keyham in #plymouth. Please can everyone stay safe, stay indoors and follow police advice."

Devon and Cornwall Police have also been contacted for more information.