The suspect has been killed, and the officers are now searching the area for any additional shooting victims. Police have not said where in the district the shooting took place.The FBI is assisting with the investigation. He added that the suspect had a long gun.
Miami Valley Hospital communications department Terrea Little said the hospital received 16 victims from the shooting.
Kettering Health Network spokeswoman Elizabeth Long said multiple victims from a shooting had been brought to system hospitals, but didn't have details on how many.
With a population of around 140,000 Dayton is in western OH, around 55 miles (90 kilometers) northeast of Cincinnati, 75 miles (120 kilometers) west of Columbus and 120 miles (195 kilometers) east of Indianapolis. The Oregon District is a historic neighbourhood that Carper described as "a safe part of downtown", home to entertainment options, including bars, restaurants and theatres.
The shooting happened as the suspect was making his way toward a bar called Ned Peppers, Montgomery County Emergency Services spokeswoman Deb Decker said. The shooting apparently happened at or near one of those establishments.
"He (a gunman) tried to get into the bar but did not make it through the door", Wilson wrote.
At least one person was shot in the abdomen and at least two people were taken into surgery.
The police have not identified the gunman or a motive for the attack.
The ATF Columbus Division said it is responding to the scene. "In our Oregon District, this is unheard of".
However, the FBI is investigating claims the alleged gunman posted a manifesto citing the mosque attacks not long before the attacks.
A family assistance center has been deployed nearby the scene.
The Saturday shooting in El Paso and the Sunday shooting in Dayton were the 21st and 22nd mass killings of 2019 in the US, according to the AP/USA Today/Northeastern University mass murder database that tracks homicides where four or more people killed - not including the offender.
The violence in OH comes just hours after a mass shooting in El Paso, where a single gunman killed 20 people and injured 26 others.
On July 28, a 19-year-old shot and killed three people, including two children, at the Gilroy Garlic Festival in Northern California.
The El Paso death toll could rise, officials said, noting that some of the dozens of people injured were in critical condition.
The Ohio shooting was the third major outbreak of USA 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. The 20 mass killings in the U.S.in 2019 that preceded this weekend claimed 96 lives.