At least nine people were critically injured early Sunday when a gunman opened fire in a busy entertainment district in Tucson, Arizona, before police officers shot him and stopped the threat, authorities said.

The shooting occurred around 2 a.m. local time in downtown Tucson, as the streets were teeming with people out for a night on the town, Officer Frank Magos, a spokesperson for the Tucson Police Department, said at a news conference Sunday.