At least five people have been killed by a gunman in the UK, before he took his own life.
Armed police and helicopters rushed to a suburb in Plymouth after locals said they heard "gunshots" shortly after 6pm (local time).
Residents reportedly heard "gun shots" and "loud bangs" before emergency services were on scene.
It is understood that there have been "multiple" fatalities, but it is not believed to be terror related at this time.
The Daily Mail reported five people had been killed by the gunman before he took his own life.
Police confirmed there were 'a number of fatalities at the scene', with other people left injured and needing treatment.
"Officers and ambulance staff attended," a spokesman told PlymouthLive.
"There have been a number of fatalities at the scene and 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."
Several of the shooter's relatives along with unconnected members of the public are believed to be among the victims, reported the Mail.
Dozens of locals have reported a "shooting" online, with footage circulating online appearing to show a bloodied victim on the ground surrounded by armed police.
In one video posted to social media an armed officer can be heard telling members of the public to "walk away" from the scene.
Police dogs are also on scene searching the area within the cordon
'A grim day'
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 MPs have described the situation s "very serious", adding that it is a "grim day" for their community.
Luke Pollard MP said: "There looks to be a very serious situation happening in Keyham. Please can everyone stay safe, stay indoors and follow police advice.
"Awaiting confirmation of number of victims but this looks like a very grim day for our city and our community.
"Please can I ask that you think of the families and our community and not share any images or videos of any of the victims."
Johnny Mercer MP added: "I am aware of a serious and tragic incident unfolding in Plymouth.
"The incident is not terror related, and neither is the suspect on the run in Plymouth. Remain calm.
"It is for the police to confirm further details. Do not repost chatter or gossip; work with them. We have the best cops in the land."
South Western Ambulance spokesman said: "We were called at 6.12pm to an ongoing incident in Plymouth.
"We responded to the incident with a significant number of resources, including Hazardous Area Response Teams, multiple ambulances, air ambulances, multiple doctors and senior paramedics."
Devon and Cornwall Police has been contacted for more information.