A second person injured in a stampede at a rap concert in Rochester, New York has died, police said, while a third remains in a critical condition.

Earlier, a 33-year-old woman died after being injured in a crowd surge as concert goers left a show headlined by Grammy-nominated artist GloRilla.

Several people were injured as audience members rushed for the Main Street Armory's exits because of unfounded fears of gunfire, authorities said.

The Memphis rap stars GloRilla and Finesse2tymes had finished performing on Sunday night when people exiting just after 11 pm began to surge dangerously, Police Chief David M. Smith said at a news briefing on Monday.

"We do not have any evidence of gunshots being fired or of anyone being shot or stabbed at the scene," Smith said.

He said police are investigating several possible causes of the fatal surge, including "possibly crowd size, shots fired, pepper spray and other contributing factors."

Mayor Malik Evans called the fatal stampede "totally unacceptable" and promised a through investigation into whether venue operators had the necessary safety measures in place for a large crowd.

"We are going to hold people accountable for what happened last night, period," Evans said, though he cautioned that it was too early in the investigation to assign blame. "I intend to get to the bottom of this."

GloRilla, a Memphis native whose 2022 song FNF (Let's Go) with Hitkidd was nominated for a Grammy for best rap performance, tweeted that she was "praying everybody is ok".

Fatal crowd surges have been a recurring disaster at concerts and other large events in the US and around the world, including one at a 2021 concert by rapper Travis Scott in which 10 people died.