One person has been killed and at least six others injured following a mass shooting at a park in upstate New York.

Rochester police said they responded to Maplewood Park on Sunday around 6:20 PM local time to a large gathering with shots fired and found several people suffering from gunshot wounds.

An adult in their 20s was killed, another person suffered a life-threatening injury and five people were hospitalised with minor injuries, Captain Greg Bello said.

The identity of the victim fatally shot has not yet been released pending the notification of the family, Bello said.

Several police agencies responded to the park including the Irondequoit Police, Monroe County Sheriff's Office, Rochester Police and New York State Police. Rochester police did confirm a party was happening in the area at the time of the shooting.

"At this point we don't know how many people were shooting," Bello said. "We are trying to work our way through as many witnesses as we can."

No suspects were in custody, police said.

Police asked that anyone with video of the shooting send it to Major Crimes or contact Crime Stoppers or call either 311 or 911 with any information.

Rochester is about 547 kilometres northwest of Manhattan.