LONDON — Police in southwest England say there have been “a number of fatalities” in the city of Plymouth after what they termed a “serious firearms incident.”

Devon and Cornwall Police said in a statement on Twitter late Thursday that several other casualties are receiving treatment following the incident, which one local lawmaker said was not terror-related.

Police have declared a “critical incident” but did not provide details of what exactly occurred in the Keyham district of the city. The area has been cordoned off.

Emergency services, including air ambulance and senior paramedics, responded to the incident at around 6:10 p.m.

Johnny Mercer, one of the city’s lawmakers, said in a tweet the incident is “not terror related, and neither is the suspect on the run in Plymouth.”