The gunman who burst into a SunTrust Bank in Florida on Wednesday made the five women he found inside lay facedown on the floor before he shot them each in the back of the head, killing them, according to an affidavit released Thursday. And when he was done, he called police to tell them what he had done.

On Thursday, police released the identities of three of the five victims — four female bank employees and one female customer — and said for the first time that a sixth person inside the bank in Sebring, Florida, escaped when he heard the shooting begin around 12:30 p.m.

The suspect, Zephen A. Xaver, 21, was arrested Wednesday and charged with five counts of first-degree premeditated murder. Nathaniel Heitkamp, a friend who said in an interview that he met Xaver five years ago at a mental health facility in Indiana, said, “He had an obsession with violence.”

Chief Karl Hoglund of the Sebring Police Department identified the customer who was killed as Cynthia Lee Watson, 65, and one of the employees as Marisol Lopez, 55.

At a news conference later in the day, a third victim, Ana Piñon-Williams, 37, was identified by her brother-in-law, Tim Williams. He said she was a mother of seven who started working at the bank recently.

“We do not know what was going on in the mind of the individual who committed this atrocious act, but we do know he was influenced by the darkness in this world,” Tim Williams said.

Police said they also did not understand why Xaver, wearing a T-shirt with an image of four scythe-wielding grim reapers on horseback, carried out the methodical killings in the small city, about 80 miles south of Orlando.

Hoglund said Thursday that Xaver did not know any of the victims and had no known connection to the SunTrust branch. The chief also said there were no signs that he had intended to rob the bank or do anything there other than shoot people.

“We believe it was a random act,” Hoglund said. “We are still trying to establish what has occurred, the gravity and nature of why it occurred, and try to put it in a perspective that we can understand.”

When officers arrived at the bank Wednesday, they found a harrowing scene, according to the police affidavit released Thursday.

Xaver, who remained on the phone with police, was barricaded inside the bank and said he had a 9 mm handgun and was wearing a bulletproof vest. What followed was a standoff that ended when an armored police vehicle rammed into the bank doors, shattering their glass, video footage shows.

Inside, police found five women lying in the lobby with gunshot wounds to the backs of their heads and upper torsos, spent shell casings littered on the floor all around them. They found Xaver hiding in an office in the back of the bank, the affidavit said.

The police initially said Wednesday that the five victims were the only people in the bank at the time of the attack, but Hoglund said Thursday that a sixth person had been on the premises when Xaver opened fire.

“There was another bank employee in the building at the time the incident began,” the chief said in an email. “The employee was in a back break room and heard the shots and ran out a back door and contacted law enforcement.”

Relatives of the two other victims asked that their names be withheld from the public, Hoglund said Thursday, adding that he would honor those requests under a new crime victims’ law in Florida known as Marsy’s Law.

The shooting Wednesday was the latest of several high-profile deadly attacks in Florida in the last year. Authorities did not say Thursday how Xaver had obtained a gun.

At a court hearing on Thursday morning, Xaver, wearing a black-and-white jumpsuit, stood before Judge Anthony Ritenour and responded, “Yes, sir,” when asked whether he had no income or assets. The judge appointed a public defender to represent Xaver, who was being held at Highlands County Jail in Sebring, and ordered him held without bond.

Xaver lived in Sebring but had spent most of his life in Plymouth, Indiana, a town about 23 miles south of South Bend, Indiana, according to Heitkamp. Xaver had recently trained to be a correctional officer at Avon Park Correctional Institution, a prison about 20 miles north of Sebring, said Patrick Manderfield, a spokesman for the Florida Department of Corrections.

Heitkamp said he had met Xaver when they were both teenagers and patients at Michiana Behavioral Health in Plymouth. A representative at Universal Health Services, the company that operates the center, did not immediately respond to a request for comment Thursday.

Over the years, Xaver complained about being bullied at school and disliked by his family, said Heitkamp, who now works in the service industry. When Xaver got upset, Heitkamp said, he openly talked about a desire to hurt people and how he had access to guns.

“This man did not hide it,” Heitkamp said.

Gracelynn Williams, 20, said she became close friends with Xaver at the same facility in Plymouth several years ago.

Reached through Facebook, Williams said Xaver had struggled with suicidal and homicidal thoughts and had a strained relationship with his parents, especially with his father.

“He mostly spoke about wanting to hurt himself,” she said.

“Society made him a monster,” she said. “Unfortunately, nobody listened to him and five lives have been lost. It’s devastating.”

This article originally appeared in The New York Times.