A gunman opened fire in a downtown district of Dayton, Ohio, early on Sunday, killing nine people and wounding at least 26 others, police and the city mayor said, in the second deadly mass shooting in the United States in less than a day.
Police who were on routine patrol nearby intervened and shot the attacker dead, Assistant Police Chief Matt Carper said.
Carper told reporters the incident began at 1 a.m. local time in Dayton's Oregon District, a downtown historic neighbourhood popular for its nightclubs, restaurants art galleries and shops.
The motive behind the shooting was not immediately clear, and investigators believe the individual had acted alone, Carper said. The authorities did not disclose the shooter's identity.
A total of 10 people were killed, including the assailant. Twenty-six others were injured and taken to hospitals across the area, Mayor Nan Whaley told reporters, though the extent of their injuries was not known.
She said the suspect was wearing body armour and was armed with a high-capacity rifle with multiple ammunition magazines.
FBI agents were assisting in the investigation.
The shooting in Dayton, a riverfront city of about 140,000 people in southwestern Ohio, came just 13 hours after a mass shooting at a Walmart store in El Paso, Texas, where 20 people were killed and 26 others wounded. The 21-year-old suspect in that shooting was arrested.
The Ohio shooting was the third major outbreak of U.S. gun violence, coming seven days after a teenager killed three people with an assault rifle at a food festival in Northern California before taking his own life.
Pope Francis condemned the attacks on "defenceless people" in the U.S. shootings in his Sunday message and blessing from St Peter's Square.
The Dayton Daily News said the latest shooting occurred at or near a tavern called Ned Peppers Bar.
The newspaper cited a Facebook post from James Wilson, who said he was a customer sitting on a patio just outside the bar when the shooting occurred in front of the establishment.
"He (a gunman) tried to get into the bar but did not make it through the door," Wilson wrote. "Someone took the gun from him and he got shot and is dead."
Video footage posted on social media showed numerous police and fire department vehicles parked in the area.