A man died earlier this morning in an incident involving police firearms on The Portbury Hundred (A369) in Portishead, Avon and Somerset Police have confirmed.
The road has been sealed off.
Police have confirmed the incident is not terror-related.
An eyewitness claims he saw police shoot into a car that had been stopped.
"As I came out of Portishead to join the motorway I got stopped. Ahead of me were police in the road. I saw them back off from a car and then they surrounded it. They maybe shot with handguns five, six, maybe 10 times. Then they dragged a man from the car to resuscitate him."
Avon and Somerset Police say motorists will not be able to access Portishead from Junction 19 of the M5.
"We anticipate the road will remain closed for some time."
The Independent Police Complaints Commission says it has been notified of an "incident" by the force.
More to follow...