A gunman opened fire Monday morning in a Delaware courthouse lobby just as the building was opening to the public for the day, exchanging shots with police and leaving three people — including the shooter — dead, authorities said.

"It happened so fast," said Jose Beltran, 53, an employee at the New Castle County Courthouse who was entering the lobby when he heard two shots. He said he turned around and heard three or more shots as he ran.

Delaware State Police Sgt. Paul Shavack said the suspected gunman and two women are dead. The city's mayor said one of the women killed was the shooter's estranged wife, but Shavack said police had not confirmed that was the case.

Shavack said did not say how the gunman died. He said two police officers suffered non-life-threatening injuries.

He said the shooting was not random, with the motive still to be determined, and he cautioned against information coming from any other source.

But Wilmington Mayor Dennis Williams said in a telephone interview that he was told the man shot and killed his wife.

Shavak said the gunman opened fire before he passed metal detectors in the lobby.

Chick Chinski, 62, of Middletown said he was entering the courthouse to report for jury duty when he heard popping sounds.

"It didn't sound like gunfire first at all," said Chinski, adding that he saw the gunman pointing his weapon.

He said it seemed that the shooter deliberately targeted the two women who were shot as they stood in the middle of the lobby.

Gunman fired as soon as he entered lobby

"Absolutely," he said. "It's right what he went after when he come in the door. That's exactly what he did instantly."

Chinski said that earlier, he shared an elevator with the gunman and others from the parking garage. The gunman was quiet and did not appear agitated, Chinski said.

In the hours after the shooting, dozens of police cars and emergency vehicles were on the streets surrounding the courthouse. Police searched the courthouse room by room as a precaution.

Dick Lawyer works part time across the street at the law office of Casarino, Christman, Shalk, Ransom & Doss and said his office building had been on lockdown since about 8:15 a.m. The shooting occurred about five minutes earlier. He said he and colleagues were shaken at first but calmer hours later. "We have a couple of people whose relatives work at the courthouse," said Lawyer, who works as a document management specialist for the firm.

He said the building was still on lockdown at 12:40 p.m.

Robert Vess, 68, dropped off his wife, Dorothy, 69, for jury duty at the courthouse Monday morning. He said it wasn't until after 10:30 a.m. that she was able to call him and let him know she was safe. Vess said his wife, who works as a baker at a grocery store, was crying when she called, but he thought she would be all right.

"She had said, `If I had my way, I'd do jury duty every day,' but I don't think so after this," Vess said.