A police cordon surrounds 10 terraced houses after a man was tasered and died at a property in Gorton.
A forensic tent was placed in Beard road within the cordon which is being guarded by uniformed officers, a police van and two patrol cars.
Assistant Chief Constable Garry Shewan said: "Police received a 999 call reporting a disturbance on Beard Road in Gorton where there was a man with a knife.
Officers were dispatched immediately and arrived in eight minutes. On arrival, a Taser was discharged."
The dead man has been named locally as Jordan Begley.
A friend of the dead man said that eight armed response officers attended the family home last night.
"They turfed his mum outside and then went in and battered him," said the man, who did not want to be named.
"There were about eight armed response officers went in. He didn't have a knife though. I know for a fact he would not have had a knife. There was no need to use a Taser on him. I think he has some problem with his heart."
The force have referred themselves to the police watchdog,
More top news
Remaining rather cool and changeable Wednesday. Most places should have a dry day on Thursday with some sunshine
Chester has a proud political legacy. But now this once-safe Tory seat is one of the key 2015 battlegrounds
St Helens player Kyle Amor and Warrington's Roy Asotasi shaved their beards to raise money for the family of Danny Jones, who died on Sunday