The suspect has not yet been named. The Reno Gazette Journal described the man as a young adult and said he was on the 8th floor of the Montage firing onto the street below.
The newspaper said at least one person was injured, with a wound to the hand.
KRNV reported that the gunman had taken a female hostage who was not injured.
Reno is about 450 miles northwest of Las Vegas, where a gunman opened fire on a country music festival last month, killing 58 and wounding hundreds.