Doves are released over gathered mourners during a vigil Sunday at the scene of a mass shooting in Dayton, Ohio. Police say the shooter opened fire in the area around 1 a.m. Sunday, killing his adult sister and eight others and injuring 27 others.

DAYTON, Ohio — Nine white doves were released at a vigil to honor the nine adults killed by a gunman in a popular entertainment district in Dayton, Ohio.

Hundreds of people, mostly young adults, gathered Sunday evening at the scene in Dayton's Oregon District. They sang “Amazing Grace” and erupted in cheers at the mention of emergency responders who had rushed to the scene.

Cyndi Johnson, who lives nearby, said the Oregon District is an area people visit to celebrate bridal showers and 21st birthdays. She says it's not scary, and she doesn't want it known that way.

Police say the shooter, 24-year-old Connor Betts, opened fire in the area around 1 a.m. Sunday, killing his adult sister and eight others. Police say he was fatally shot by officers within 30 seconds. Authorities say 27 others were injured.

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.

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

Betts was known at a local bar as an ever-friendly, happy guy who sometimes came in for a beer or two and was never a troublemaker.

Fellow customer Mike Kern said he sometimes played trivia with Betts at Romer's Bar & Grill in Bellbrook, Betts' hometown southeast of Dayton. Kern said Betts often knew answers about current events and pop culture and never discussed violence.

Kern described Betts as “the nicest kid you could imagine.”

Bartender Andy Baker said Betts was at Romer's last Monday and seemed fine. Baker said when he saw Betts identified as the shooter in the early Sunday massacre in a popular entertainment district, he thought: There's no way that's the guy.

Authorities say the shooter was wearing a bulletproof vest, mask and hearing protection and carrying at least 100 rounds when he opened fire.

Police Chief Richard Biehl said Betts killed his sister and eight others in less than 30 seconds before police fatally shot him.

Biehl said he can't yet answer why Betts began shooting.

Biehl said the .223-caliber rifle Betts used was ordered online from Texas and transferred to Betts at a firearms dealer in the area.

It was the second U.S. mass shooting in less than 24 hours.