CHICAGO — A man showed up at Mercy Hospital on Monday afternoon and opened fire on his former fiancee before turning the gun on others, killing the woman, a police officer and a bystander. The gunman also died at the scene.

The incident, witnesses said, began in the hospital’s parking lot as a domestic argument involving the gunman, identified by police as 32-year-old Juan Lopez, and Tamara O’Neal, a 38-year-old emergency room physician.

When a friend attempted to intervene, Lopez lifted his shirt to display a handgun, Chicago Police Superintendent Eddie Johnson said. According to the Associated Press, O’Neal’s friend then “ran into the hospital to call for help, and the gunfire began seconds later.”

O’Neal was killed in the parking lot, authorities said.

A family member told ABC 7 Chicago that Lopez and O’Neal were engaged for about a year but that their wedding was called off in September. The Chicago Tribune reported that O’Neal had broken off the engagement and that Lopez went to the hospital Monday afternoon to demand his ring back.

According to the AP:

When officers arrived, the suspect fired at their squad car and then ran inside the hospital. The officers gave chase.

Inside the hospital, the gunman exchanged fire with officers and “shot a poor woman who just came off the elevator” before he was killed, Johnson said.

Police Officer Samuel Jimenez was killed during the shootout, police spokesman Anthony Guglielmi confirmed. Jimenez had joined the department in February 2017. He was married and had three children.

Dayna Less, a 25-year-old pharmacy resident and bystander, also was fatally shot as she left an elevator, authorities said. ABC 7 reported that Less was a graduate of Purdue University and was planning on traveling home to Indiana on Tuesday to be with her family on Thanksgiving. She was engaged and set to be married next summer.

“The city of Chicago lost a doctor, pharmaceutical assistant and a police officer, all going about their day, all doing what they loved,” Mayor Rahm Emanuel said, fighting back tears after the shooting. “This just tears at the soul of our city. It is the face and a consequence of evil.”

It was not immediately known whether Lopez killed himself or died by police fire.

According to the Chicago Tribune, Lopez had threatened to shoot up the Chicago Fire Academy nearly five years ago, after he was terminated for “improper conduct” toward women there.

Fire Department spokesman Larry Langford told the Tribune that Lopez was accused of “aggressive and improper conduct toward females at the academy,” leading to his firing.

“He had issues, he was not getting along well,” Langford said. “He did not successfully complete his training and was terminated before he finished the academy."

During the attack, a SWAT team responded to the 292-bed hospital near Interstate 55, in the city’s Bronzeville neighborhood. Nearby buildings, including the National Teachers Academy, were locked during the attack. Mercy Hospital tweeted later that the incident was over and that all patients were safe.

Lenice Donaldson, a pharmacy technician at Mercy, said she was in the back to get a drink and had just returned when Ashe heard the gunshots. She and the other technicians locked themselves up until police got them out, she said.

“It’s just unbelievable. We came out with our hands up, and there was blood all over the floor in the lobby,” Donaldson said. “It’s a shame.”

Tracy Lyons, a cancer survivor, said she goes to Mercy for regular radiation treatments. She described listening to the gun battle between police and the shooter until a SWAT team freed her and some technicians from a lab.

“It was just nothing but pow-pow-pow,” she said. “We thought we would never get out of there."

Sen Richard J. Durbin (D-Ill.) wrote in a Monday evening tweet that he was praying for the victims of the shooting and their families.

Also Monday, according to the St. Louis Post-Dispatch, police in suburban St. Louis were searching for a gunman who they say went into a religious supply store, sexually assaulted at least one woman and shot a woman in the head, leaving her in critical condition at a hospital.

The shooting occurred about 3:15 p.m. at a Catholic Supply store in western St. Louis County, near the town of Ballwin. Police were searching for the gunman and said he should be considered armed and dangerous.

In Philadelphia, two men and two women were “executed” in a home, according to ABC. And in Denver’s Lower Downtown neighborhood, one person was killed and at least three others were sent to a hospital after a shooting, according to the Denver Post.

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