Twelve people, including a 12-year-old child, were injured when what is believed to be a shotgun was fired in a large crowd of people at a street party, police have said.
Officers were called to reports of two loud bangs at the party, which followed Manchester's Caribbean Carnival, on Claremont Road in Moss Side in the early hours of Sunday morning.
Greater Manchester Police said nine people, including two children who were at the street party with parents, were taken to hospital after suffering pellet injuries, predominantly to their legs, while one man sustained a broken leg, the cause of which is not known.
Two further people presented themselves at hospital for a check up on Sunday but their injuries were not thought to be serious.
A force spokesman said out of the 12 people who had been to hospital, seven had been discharged, including a teenager.
Chief Superintendent Wasim Chaudhry said police had launched an attempted murder investigation but the motive for the attack remained unclear.
'This could have been far worse'
He said: "In the early hours of today, at around 2.25 this morning, my officers got a report of the sound of two loud bangs in the Claremont Road area of south Manchester and officers were quickly in attendance, within a minute in fact.
"They were both armed officers that attended and also unarmed staff.
"What they were faced with was a large crowd of… several hundred people in the area who were continuing to celebrate the Caribbean Carnival and a number of those people had been injured and there was a state of panic which our officers had to contend and deal with."
Mr Chaudhry said police were working on the "hypothesis" that there was a shotgun discharge, but it was not clear how many times the weapon had been fired.
He said: "We can't minimise the risk that the public were put into and the fact that this could have been far worse.
"We could have been dealing with life-threatening injuries and we could indeed be investigating multiple murders.
"It's unclear at this stage what the motive, what the reason behind this attack was, however I've got to be clear, it would be obvious to any particular person that discharging a firearm in a large crowd like this is completely reckless."