LONDON — There have been multiple fatalities in a “serious firearms incident” in Plymouth, a port city in Devon, southwest England, with several other casualties receiving treatment, police have confirmed.

Home secretary Priti Patel tweeted: "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."

Plymouth Sutton and Devonport MP Luke Pollard said it was "a very grim day for our city and our community".

The Labour frontbencher said he was "awaiting confirmation" of the number of victims.

Plymouth Moor View MP Johnny Mercer also said on Twitter that the incident is "not terror-related," adding that the suspect involved is "not on the run".

South Western Ambulance Service said it was responding with "Hazardous Area Response Teams (HART), multiple ambulances, air ambulances, multiple doctors and senior paramedics". — Agencies