Another mass killing happened overnight in Ohio, just hours after El Paso Walmart tragedy

Nine people were murdered and more than two dozen others were injured in Dayton, Ohio, early Sunday morning, the second mass killing in the U.S. in less than 24 hours.

The shooting erupted shortly after 1 a.m. in Dayton's historic downtown Oregon District, a popular nightlife destination full of restaurants and bars. Fortunately, nearby officers "put an end to it quickly" by shooting and killing the suspect, Dayton Police Lt. Col. Matt Carper said, the Associated Press reported.

Dayton Mayor Nan Whaley said at a press conference the killer used a .223 caliber rifle, had additional high-capacity magazines, and was wearing body armor.

"If Dayton police had not gotten to the scene in under a minute, hundreds of people in the Oregon District could be dead today," Whaley said, Fox News reported.

At least 26 people are being treated at area hospitals for injuries related to the incident, officials said.

The FBI is assisting local and state authorities with the investigation. Authorities do not yet know a motive.

Taylor Mayberry — who was at the Ned Peppers bar, where the shooting occurred — told NBC News she hid in the bar's bathroom when shots rang out.

"I just heard a few gunshots and then saw everyone jumping to the ground," she said. "I've never experienced anything like that, so I dove to the ground and started running to the bathroom. I saw people trying to move toward the exit."

"We were holding the door shut and waiting until the gunshots stopped," Mayberry added. "People were banging on the doors throughout. We weren't sure if they were … you know … we weren't sure if it was people getting in to shoot us or to get safe."

Nikita Papillon, who was across the street at a different bar, told the AP she saw a young women lying on the ground who she had just spoken to hours earlier.

"She had told me she liked my outfit and thought I was cute, and I told her I liked her outfit and I thought she was cute," Papillon said. "People my age, we don't think something like this is going to happen. And when it happens, words can't describe it."