A man has been arrested on suspicion of attempted murder after a man fell from a balcony.
Police were called to reports that the man had fallen at flats on Liverpool Street in Salford shortly after midnight on Saturday, Greater Manchester Police (GMP) said.
Emergency services attended and the man was taken to hospital with life-threatening injuries, where he remains in a critical condition, the force said.
A man in his 20s has been taken into police custody for questioning.
The incident has been referred to the Independent Office for Police Conduct (IOPC) because the men had earlier contact with police, GMP said.
A blue forensic tent has been erected near to a building on the corner of Liverpool Street and Southern Street.
A local resident, who did not wish to be named, said she heard sirens overnight and saw the aftermath of the incident being live-streamed on social media.
She said: “I heard all the sirens, but I keep myself to myself so I didn’t go out.
“I’ve seen it’s all cordoned off and there’s a blue forensics tent.
“It’s sad, it’s really sad. It’s a bit close to home.”
Ch Insp Lee Gridley said: “A man has been arrested on suspicion of attempted murder, and he is currently being questioned in custody.
“Our officers are working at pace to establish the full circumstances, and a scene will remain in place whilst the investigation continues.
“We understand that incidents of this nature may cause concern within the community, however we believe this is an isolated incident and that there is no wider risk to the public.”
An IOPC spokesperson said: “After being notified by the Greater Manchester Police of the previous police contact with the parties involved in this incident, we sent investigators to the police post-incident procedures in Manchester in assessment mode to gather further information.
“We continue to remain in assessment mode and will assess a GMP referral in due course.”