The shooter who killed nine people, including his own sister, and injured at least 27 others when he opened fire on a popular nightclub district in Dayton, Ohio, wore a bulletproof vest, mask, hearing protection and was carrying at least 100 rounds of ammunition, police said Sunday.

Police identified the shooter as 24-year-old Connor Stephen Betts of Bellbrook, Ohio. He was shot and killed by police within 30 seconds of opening fire on the streets of the Oregon District of Dayton around 1 a.m. Sunday, Dayton Police Chief Richard Biehl told a press conference Sunday afternoon.

"We are very, very early into this investigation. Any suggestion at this time of motive would be irresponsible," he said. "We do not have sufficient information to answer the question everyone wants to know — why."

Betts's sister, Megan Betts, was the youngest of the victims, who ranged in age from 22 to 57. Biehl said she and a male companion were among the first people shot as her brother emerged onto 5th Street from an alleyway near Ned Peppers Bar.

This was the second mass shooting in the U.S. in less than 24 hours. It came just hours after a young man opened fire in a crowded El Paso, Tex., shopping area, leaving 20 dead and more than two dozen injured. Read more about that here.

The nine victims in Dayton have been identified, including four women and five men among the victims.

Six of the nine people killed were African-American.

The victims include:

Megan Betts, 22. Betts worked as a tour guide at the Smokejumper Visitor Center in Missoula, Mont., this summer. Manager Daniel Cottrell told the Washington Post she was a "very positive person" who was well-liked by her peers. Her mother picked her up at the end of the internship.

Monica Brickhouse, 39.

Nicholas Cumer, 25. Cumer was a graduate student in the master of cancer care program at Saint Francis University in Pennsylvania. University president Father Malachi Van Tassell said Cumer had been in Dayton as part of an internship program.

Derrick Fudge, 57. Fudge's sister, Twyla Southall, told the Dayton Daily News that he was out with family when he was killed. "They were all just down there enjoying themselves and had stepped out of, I think, one of the clubs and were in a line to get some food," she said. She said that Fudge, who lived in Springfield, "was a good man and loved his family."

Thomas McNichols, 25. McNichols, who went by T.J., was a "gentle giant," according to an aunt. Donna Johnson told WSOC TV that he was out with a cousin after working at a factory when the shooting occurred. His four children range in age from two to eight years old.

Lois Oglesby, 27. Oglesby was described by a cousin as a "wonderful mother, a wonderful person" who was looking forward to a career as a nurse after she finished her degree.

This is Lois Oglesby.<br><br>She was one of the victims of the <a href="https://twitter.com/hashtag/DaytonMassShooting?src=hash&ref_src=twsrc%5Etfw">#DaytonMassShooting</a>. She works at a daycare and is a mother. She leaves behind a daughter and a newborn baby.<a href="https://twitter.com/hashtag/DaytonStrong?src=hash&ref_src=twsrc%5Etfw">#DaytonStrong</a> <a href="https://t.co/9GZzOykNSa">https://t.co/9GZzOykNSa</a> —@KristenClarkeJD

Saeed Saleh, 38.

Logan Turner, 30. Turner's mother described him as the "world's best son." She told the Dayton Daily News that Turner, who lived in Springboro, had just celebrated his 30th birthday on Tuesday and was working as a machinist.

Beatrice Warren-Curtis, 36.

CBC will update with details on the victims as we learn more.

The police chief said Betts and his sister travelled to the area together by car registered to their father earlier Saturday night.

The weapon the shooter used was previously identified as a AR-15 assault rifle similar to ones employed in previous mass shootings in the U.S. Bheil told reporters there was nothing in Connor Betts's history that would have prevented him from owning the gun, whch was ordered online from Texas and delivered to an Ohio firearms dealer.

Police release video of mass shooting in Ohio. WARNING: Graphic content

Law enforcement officials have released surveillance video of the mass shooting in Dayton, Ohio, including footage of officers engaging with the gunman before he was killed. 3:44

"This is a heartbreaking tragedy and it is the type of tragedy you pray never comes to your state or to your community," Ohio Gov. Mike DeWine told a news conference Sunday afternoon.

The popular entertainment district has been cleared of crime-scene tape and opened to a sombre crowd attending a Sunday evening vigil.

Some people milling about brick streets in the Oregon District left flower bouquets in front of the bars. At one store, a few purple flowers were tucked into a bullet hole.

Mourners place flowers and candles at the front of Ned Peppers bar gathering at the scene of a mass shooting before a prayer vigil Sunday night. (John Minchillo/The Associated Press)

More holes were visible in the window at Ned Peppers Bar, where police killed the shooter just outside the doorstep to save those inside.

Earlier in the day, DeWine said the shooter was close to being able to kill "dozens and dozens" of people.

'There was a lot of rounds'

Tianycia Leonard, 28, was in the back, smoking at Newcom's Tavern nearby when she heard "loud thumps" that she initially thought was someone pounding on a dumpster.

"It was so noisy, but then you could tell it was gunshots and there was a lot of rounds," she said.

'People just started running': Witnesses describe deadly shooting:

Witnesses describe the chaotic scene at a bar in Dayton, Ohio, after a gunman opened fire, killing nine and injuring dozens. 1:12

With a population of around 140,000, Dayton is in western Ohio, around 90 kilometres northeast of Cincinnati, 120 kilometres west of Columbus and 195 kilometres east of Indianapolis.

Mayor Nan Whaley said the city has had its share of hardship recently, with tornadoes destroying or damaging hundreds of homes and businesses in the region on Memorial Day night (May 25).

"What really goes through my mind is one [disaster] seems completely preventable and I just question, when is enough enough?" she added.

The FBI is assisting with the investigation. U.S. President Donald Trump says federal law enforcement is working with local authorities to investigate.

'I'm heartbroken'

"We condemn these hateful and cowardly acts," Trump said in a statement.

"Through our grief, America stands united with the people of El Paso and Dayton. May God be with the victims of these two horrific crimes and bring aid and comfort to their families and friends."

The president said the U.S. flag will be flown at half-mast at the White House, all public buildings and military posts until Aug. 8.

As the investigation continued Sunday afternoon, Democratic Sen. Sherrod Brown told reporters he has asked U.S. Majority Leader Mitch McConnell to bring the Senate back during August to try and pass a bipartisan firearms background check bill.

"There's just no reason we shouldn't be doing that," he told reporters in Dayton. "Congress needs to be doing something."

Republican Sen. Rob Portman said there is also a larger mental health crisis facing the United States that must be addressed on all levels.

"There's something deeper going on here," he said at an afternoon news conference. "We also have to look deep into our hearts."

Police look for evidence after the early Sunday morning in Dayton, Ohio. (Marshall Gorby/Dayton Daily News via AP)

"I'm heartbroken," Whaley tweeted around 6 a.m. ET Sunday, thanking first responders for their efforts.

By Sunday afternoon, more than 70 mayors from across the United States had reached out to her, including those in Orlando and Pittsburgh, which were affected by previous mass shootings.

"I have to say that unfortunately because we have so many of these incidents, there is a bevy of mayors who are able to give great advice and feedback,' she said. "I think that's, quite frankly, a little sad if you think about it — that they've learned so much because all of their communities have gone through these terrible mass shootings."

Sunday's shooting in Dayton is the 22nd mass killing of 2019 in the U.S., 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 20 mass killings in the U.S. in 2019 that preceded this weekend claimed 96 lives.