Greater Manchester Police were called to Claremont Road at about 2.30am on Sunday and discovered several people had been hurt in the incident.
The force said most of the injuries did not appear to be life-threatening.
A number of people were in the area following the Caribbean Carnival, which had finished some hours before, the force added.
Detective Superintendent Debbie Dooley said: "We currently have a number of people in hospital all being treated for different injuries but thankfully most do not appear to be life-threatening at this time.
"Officers are trying to establish exactly where this incident took place and who is responsible for such a dangerous attack.
"Those living or visiting the area will understandably be concerned by this incident and we will have extra officers patrolling the area throughout the morning and into the coming days."
Claremont Road was cordoned off by police on Sunday morning.
Litter including empty bottles of brandy and other drink containers, food wrappers and nitrous oxide canisters could be seen across the street.
Residents said a street party was held annually on the road after the Caribbean Carnival in nearby Alexandra Park.
Youth worker Kemoy Walker said he was shocked at the news.
He said he had been on the main stage at the carnival on Saturday and had been at another street party on Claremont Road until about 11.30pm.
He said: "The party I was at was beautiful. When I left there was lovely dancing. That's Moss Side, that's the culture. I'm in shock this morning."
He said he believed the carnival would go ahead as planned on Sunday.
"We need to get the message across to young people to make sure they are not getting involved in negativity," he said.
He added: "Moss Side has come such a long way and there are great things happening in our community now. Hearing this, I just think why is this happening."
Greater Manchester Police (GMP) said nine people, including two children, were taken to hospital with pellet-type wounds that are not believed to be serious.
A tenth person - a man - is in a stable but serious condition with injuries to his legs.
Chief Superintendent Wasim Chaudhry, from GMP's City of Manchester division, said: "Thankfully the injuries suffered do not appear to be as serious as first believed and hopefully people will begin to leave hospital over the course of the day following treatment.
"That being said, there may be people who didn't seek treatment last night and I would urge these people to get immediate medical attention if that is the case.
"This was a reckless act that could have had devastating consequences with families and friends losing loved ones."
He added: "Today the community is likely to feel concerned and that's completely understandable.
"Guns have no place on our streets and we want to assure you we are doing everything we can to find the person or people responsible."