Deputy Police Commissioner Kevin Bethel said Friday that he did not know yet whether Bey, who had no arrest record, had been diagnosed with a mental illness, but "clearly, we had someone who had a diminished mental condition."
Though he cautioned that the investigation was just beginning, Bethel said Bey might have wanted police to kill him.
"Obviously, he was looking for something to happen," Bethel said at a news conference.
At 6:24 a.m., police received a call reporting that a gunman was shooting at parked vehicles in the first block of North Broad Street, Bethel said.
When officers arrived, Bey fired at a patrol car, Bethel said. The officers took cover and called for additional police, who cordoned off the area. SEPTA halted service around City Hall.
In front of the Masonic Temple, "he paces for approximately 30 to 40 minutes," shouting expletives while officers repeatedly ordered him to drop the gun, Bethel said.
Bey then fired one shot - the last round in his five-shot revolver - toward a group of officers, Bethel said. Each of the 16 officers who responded fired from one to four shots each.
It was the second high-profile incidence of gun violence in Center City in about 36 hours.
On Wednesday shortly before 9:30 p.m., a boy, 16, shot two other teens just blocks from the crowds gathered on the Parkway, police said. The teenage shooter, identified as Nafis Scott, tried to flee, but police caught up with him near 17th and Arch Streets, police said. An officer fired at Scott, grazing his chest with a bullet.
Friday morning's standoff shocked eyewitnesses, who gave accounts of a man in a green T-shirt nonchalantly displaying a handgun on Broad Street between Arch and City Hall.
William Underwood, 43, of Center City, was drinking coffee in the McDonald's at Broad and Arch when he saw the man through a window.
"We noted the guy had a gun," Underwood said. "He wasn't really pointing it at anyone. He just kind of had it in his hand. He was walking back and forth in front of the church. It was kind of weird."
He said employees locked the doors as police converged.
"He raised the gun, and they shot him," Underwood said. "I'd never seen anything like that in my life. . . . There were so many shots fired, it was like the Fourth of July."
A SEPTA bus driver who would not give her name said she had stopped her southbound bus at Broad and Arch for a light when "I heard a gunshot." She said the gunman fired several shots, but police did not immediately return fire.
"They gave him ample time to put down the gun and surrender," she said. "He raised the gun in the air, and that was it. It seemed like every one of the officers let go. I'd never seen anything like it. It was like a movie."
Police and witnesses said the man had fired at least two shots through a window of the Masonic Temple.
Chuck Holloway, 62, of Fishtown, was working security and maintenance at the temple when he heard two loud bangs about 6:30 a.m. He went to check and saw two bullet holes in a window.
"I looked out the window, and he was standing behind my car. I saw him standing there with the gun at his side, and all the officers, guns drawn, pointed directly at him."
Contact Julie Zauzmer