Gunshots and chaos erupted in the heart of Cincinnati's downtown Thursday morning when a man opened fire in the lobby of Fifth Third Center, killing three people and wounding two others.

Dozens of police officers rushed to the scene and exchanged gunfire with the suspect as a crowd of people who had been on their way to work scattered across Fountain Square to safety.

Killed were Prudhvi Raj Kandepi, 25, Richard Newcomer, 64, and Luis Felipe Calderón, 48, said Hamilton County Coroner Dr. Lakshmi Sammarco. There was not much information provided by authorities regarding the victims.

Police said the gunman, Omar Santa Perez, 29, was shot and killed by police officers after a brief gun battle.

The four fatalities, including Santa, make this one of the deadliest mass shootings in Greater Cincinnati in years.

"It's hard for it all to sink in, but it really did happen," Mayor John Cranley said. "This is clearly an act of grotesque violence to innocent people, and it should frighten all of us."

When the shots first rang out just before 9:11 a.m., people ran or scrambled to take cover. Many were getting their morning coffee or a doughnut before work when they heard gunshots and screams.

"There was definitely a lot of blood," said Zach Fritzhand, who saw police taking victims out of the building.

Michael Richardson was smoking in front of the building when he saw Santa open fire in the lobby. He said police officers rushed in moments later.

"A bunch of cops were coming in with guns," he said. "I saw a lady down. A Cincinnati police officer dragged her out of the bank. She was talking. She was bleeding. Her shirt was red."

Hamilton County Prosecutor Joe Deters said the suspect used a 9 mm handgun, and Police Chief Eliot Isaac said the gunman was carrying hundreds of rounds of ammunition.

"He could've killed over 100 people," Deters said.

Cranley praised the quick response from police and said he regretted Cincinnati had joined the growing list of American cities that have experienced mass shootings in the past year.

"There's something deeply sick at work here and we as a country need to work on it," Cranley said.

Police provided little information about Santa, though bank officials said Santa was not a current or former Fifth Third employee.

According to records available online, Santa was a North Bend resident who previously lived in South Carolina and Florida and may have been a college student in the Cincinnati area.

Isaac said investigators have not established a motive, but they are confident Santa acted alone. He said Santa has lived in the Cincinnati area since at least 2015.

"This is a horrific incident," Isaac said. "We are still processing the evidence and looking for any opportunity to get any greater insight into the motive."

The evidence includes footage from body police cameras and security cameras from around Fountain Square and Fifth Third Center. Police confirmed officers and Hamilton County sheriff's deputies have searched the suspect's residence in North Bend on Miami Avenue.

Officers could be seen removing items from the residence Thursday afternoon.

Isaac said Santa entered the downtown building, which is Fifth Third Bank's corporate headquarters and home to several other offices, through the loading dock and began firing shots almost immediately.

"He proceeded to the lobby, where several of our officers engaged him," Isaac said. "There were gunshots exchanged.

"It's a very horrific situation."

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Friends and colleagues confirmed that Richard Newcomer, a construction contractor working in the building, was among the dead.

Newcomer had worked at Gilbane Building Co. for three years and was a superintendent of a project going on at Fifth Third Center.

"It's such a tragedy. There are no words to describe how we're feeling," said Wes Cotter, a spokesman for the company. "Our thoughts and prayers are going out to his family."

Another victim, 37-year-old Whitney Austin, suffered 12 gunshot wounds and survived, according to her neighbors in Louisville.

Isaac said all of the shooting occurred in the lobby of the building, which was placed on lockdown until police secured the area and determined the gunman had acted alone.

He said at least three and possibly four officers exchanged fire with Santa. None of the officers were injured.

Deters said the officers initially fired through the lobby's glass windows to get to the gunman.

Police cordoned off the square and closed streets while witnesses were evacuated to the Westin Hotel lobby across the street. Firefighters and paramedics who tended to victims wore bright red body armor.

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All of the victims were transported to University of Cincinnati Medical Center, where two died. Two others, including the gunman, are believed to have died at the scene.

Two others survived the shooting: One was upgraded to fair condition and the other remained in critical condition as of Thursday afternoon.

Mark Friedman said he saw two of the shooting victims receiving treatment near Fountain Square shortly after he heard the gunshots.

"I heard two pops, like cap guns, and saw people running," Friedman said. "We just started running."

At the hospital, doctors and nurses scrambled to treat the wounded.

"Our physicians and staff are focused on caring for the patients and their families. We prepare for situations like these and hope they never happen," said UC Health spokeswoman Amanda Nageleisen. "Our thoughts and prayers are with the victims, their families and all involved."

Witnesses on the square said the gunshots seemed to come in waves of four to 10 shots. They said the shooting would stop for a short time, possibly while Santa reloaded, and then resume.

Michelle Parks, who works at Servatii's at Fifth Third Center, said she and several customers hid in the bathroom for about a half hour until they were sure the shooting was over.

"It wasn't the typical morning," Parks said. "Biggest thing is, we just want to make it home safe to our families."

About a block and a half away, Sheldon Wells was eating at a restaurant when a woman approached him.

"Stay away from the windows," the manager told him.

He watched people sprinting down the street, and overheard a person describing watching a woman exit the nearby Graeter's shop, her shirt covered in blood.

"It happened so fast," he said.

Leonard Cain said he saw a woman wearing headphones get shot as she entered the building. He said she dropped to the ground, and everyone started running.

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Emily Rash and Gretchen Pleuss, sisters visiting from North Carolina who grew up in Ohio, were walking near the crime scene about 30 minutes later. They'd also been in a restaurant that had been locked down during the violence.

"It's giving me anxiety. My heart is beating fast," Rash said. "It was kind of surreal. You're heightened, watching everybody."

Tim Nichols was directly across Fifth Street, having breakfast in the atrium between the U.S. Bank Tower and The Westin. Five or six people rushed into the building, seeking shelter.

Later, he spoke to his wife and 2-year-old son on FaceTime, "telling them I'm safe."

Shootings in Greater Cincinnati

The incident at Fifth Third is the 15th mass shooting (defined as having at least four victims) in the Cincinnati area since 2013.

It also is the deadliest mass shooting since 2013, with four dead. The March 26, 2017, mass shooting at the former Cameo nightclub in the East End had the highest casualty toll, with two people were killed and 15 shot.

Earlier this year, four people were shot on May 25 on Ross Avenue in East Price Hill after a dispute in a dice game.

With today's victims, 90 people have been injured locally in mass shootings since 2013 with 13 fatalities and 77 wounded, according to an Enquirer analysis of data kept by Gunviolencearchive.org.

There were four active shooter incidents in Ohio in 2016 and 2017, when there were 50 nationwide.

Two of Ohio's active shooter incidents were local. They were:

Dec. 20, 2017 - Isaiah Currie, 20, armed with two handguns, began shooting in the lobby of the psychiatric emergency services wing of the University of Cincinnati Medical Center in Corryville. The shooter struggled with and shot an unarmed security guard and fired several shots at a responding off-duty law enforcement officer working security nearby. No one was killed; one was wounded (an unarmed security guard). Currie committed suicide as additional law enforcement arrived.

Feb. 29, 2016 - James "Austin" Hancock, 14, armed with a handgun, allegedly began shooting in the cafeteria of Madison Junior/Senior High School in Madison Township, Butler County. He shot two students before fleeing the building. No one was killed; four students were wounded (two from shrapnel). The shooter was apprehended near the school by law enforcement officers.

Bob Strickley contributed.