The woman who went on a shooting rampage at the KSL television studios Thursday, terrorizing hundreds in the Triad Center complex and wounding two people, has a history of mental troubles, a criminal history and is well-known to the Salt Lake City police department.

De-Keiu Duy, 24, boarded a city bus with a .9mm handgun and a shopping bag full of bullets Thursday, bound for KSL because she believed the television station was harassing her, Salt Lake City police Chief Reuben Ortega said.She opened fire about 3:30 p.m, discharging dozens of bullets on the first, second and fourth floors, before her gun misfired and an AT&T employee wrestled her to the ground.

Duy was booked for investigation of two counts of attempted criminal homicide, second-degree felonies.

AT&T officials declined to release the name of the man who stopped the woman's shooting spree, saying their efforts were focused on human resource manager Anne Sleater, who was critically wounded.

Sleater, 30, who only recently returned to work after maternity leave, was shot in the head. She underwent emergency surgery in LDS Hospital Thursday and was listed in "extremely critical" condition Friday morning, hospital spokesman Jess Gomez said.

A second victim, KSL building manager Brent Wightman, was grazed by two bullets and was treated and released from Salt Lake Regional Medical Center Thursday night.

"We are extremely fortunate more people were not injured," Ortega said. "She was carrying enough ammunition to do a lot of damage."

Duy, who was born in Vietnam but reared in Salt Lake City, has a history of psychological problems and sometimes "hears voices," her mother, Khanh Duy said Thursday night.

Khanh Duy said her daughter has undergone treatment for mental disorders in the past.

"She is a good girl, but she has problems. She hears voices," the mother said.

De-Keiu Duy dropped out of an outpatient treatment program at Valley Mental Health last summer, center public relations director Connie Hines said. She was not in the program under a court order, Hines said.

Police dispatchers from Salt Lake City said they had spoken with De-Keiu Duy regularly for many years and that she always used the name "Sabrina." She always seemed confused and troubled, rambling about aliens and people wanting to harm her, a dispatcher said.

Police were sometimes sent to the family home De-Keiu Duy shared with her mother and three siblings. De-Keiu Duy was also red-flagged in the dispatch computer system as a frequent caller.

"But she never, ever said she wanted to hurt anyone or seemed like a threat," one dispatcher said. "We were all so surprised when we found out it was her."

De-Keiu Duy's criminal history includes an arrest in West Valley City in 1996 on charges of stalking, disorderly conduct and interfering with an arrest. She was also charged with carrying a concealed weapon.

"(De-Kieu) used to get in trouble and argue with police officers," said Khanh Duy, who learned about the shooting when police telephoned her after she arrived home from work Thursday. She told officers, "She (her daughter) spent some time in jail. After she went to university, she started doing better. I don't know why today she had trouble again."Police and witnesses gather near entrance to KSL's Broadcast House in Salt Lake City Thursday after a woman entered the building and began shooting.Laura Seitz, Deseret News

Records from the University of Utah indicate De-Keiu Duy was enrolled at the school from 1993 through 1997 as a pre-medicine major. She dropped out of school in 1997 as a sophomore.

Khanh Duy said she has never heard her daughter say anything about KSL or its employees. She had no idea why her daughter would open fire in the studios. She did not know her daughter owned a gun.

KSL receptionist Colleen Mirci, 68, was the first to cross De-Keiu Duy's path in the Triad Center Thursday. While the shooter's motives remained unclear Thursday night, it was clear she intended to harm someone at the television station, Ortega said.

De-Keiu Duy demanded access to the newsroom and then drew a gun, Mirci said. The woman was wearing a large tan coat and the type of ear protection gear that is typically worn at shooting ranges. A hood partially covered her face and head.

"She reached down to her waist and pulled out a gun," Mirci said. "She pointed it at me and said, 'I'm going to kill you and I'm going to kill that b---- in the newsroom.' "

Then Wightman saw what was going on and got involved, Mirci said. He asked the woman with the gun if she wanted to sit down and talk about the situation, but she kept asking where the newsroom was.

Wightman told reporters, "I heard Colleen say, 'You want to go to the reception area of news?' And she said, 'you can't go in there.' The lady stepped back from the reception desk and reached and brought out a gun and pointed it right at Colleen, and told her, 'I want to go to the newsroom.' They were four-letter comments."

De-Keiu Duy was becoming increasingly agitated, spinning around and talking incoherently, Wightman said.

Just then Mary Kammeyer walked out of the newsroom.

"I walked out and the gunman pointed the gun to my face and said, 'Newsroom, newsroom. Where's the newsroom?" said Kammeyer, a KSL Radio employee. "(Duy) pointed the gun to the floor and fired a shot near my foot. I knew I couldn't let her in (to the newsroom), so I pointed to the opposite direction. When she turned around, I shut the door and ran through the newsroom yelling, 'Gunman. Call 911.' "

Kammeyer said she hated to leave the two in the lobby with the assailant, but she knew there were about 40 employees in the newsroom. She acted to protect the people behind the door, she said.KSL and Delta Center employees await news of the shooting near Triad Center. A 24-year-old woman opened fire, wounding two, one critically.Laura Seitz, Deseret News

As she ran through the newsroom, she heard several gunshots behind her. Mirci took cover when the shots started ringing out.

"Glass was shattering everywhere," Mirci said. "I thought the lady had killed Mary."

That's when the woman with the gun opened fire on Wightman.

"Brent was in front of my desk eight to 10 feet," Mirci said. "He got shot three times. I just hid under my desk and stayed there until I heard security say she was on the elevator.

"I got up and Brent was gone. I started answering phone calls again. I took seven or eight calls. Then I heard some more gunshots so I dove back under the desk and thought, 'When are the police going to come?' "

In the meantime, dozens of employees in the newsroom were evacuating the building. Pat Winborg, a newsroom receptionist, said the employees went out a back door and then to the Delta Center across the street.

"The first thing I heard was the alarm," Winborg said. "Then we heard people screaming, 'Get out of here.' "

De-Keiu Duy went from the first floor in an elevator to the second and then the fourth floor. She fired shots in both locations. She shot Sleater on the fourth floor.

Both KSL and AT&T have security doors, which require access codes or electronic pass cards, police said. It is still unclear how De-Keiu Duy breached AT&T's security door.

KSL television, which airs on Channel 5, was off the air for a few minutes, then ran national feed of President Clinton's impeachment hearings non-stop for more than 90 minutes. The leading television station in the Salt Lake market, KSL was unable to cover the story unfolding under its own roof, although police eventually escorted employees back into the building so that broadcasts could resume.

KSL Radio returned to the air first, when a shaky Scott Seeger first broadcast interviews and updates on the shootings.

The incident sent everyone at work in the Triad Center into a tailspin.

Dan Nestel, an employee of Video West Productions, said he was in a nearby room when the shooting began. He heard two shots and a coworker entered saying "there is a gun in the lobby and I'm not kidding."

"Being stupidly curious, I came out to see," Nestel said.

He saw the woman holding a gun, wearing a hood and shooting range ear muffs, and saw her shoot twice at the KSL building manager, who had apparently been trying to settle a dispute.

As the woman became enraged and started "stalking the lobby," Nestel began to close the doors within his reach to try to contain the area, he said. While doing so, he saw a KSL reporter shut the doors into the newsroom and the woman shot in that direction.

Nestel said he ran to the second floor and people had begun to leave their work areas.

"There were people everywhere" trying to leave the building through emergency exits, he said.

Then, "she shot at me three times," Nestel said. "That's when I said 'it's time to get out of here.'"

Lucinda Dillon, Jenifer K. Nii, Hans Moran and Douglas D. Palmer contributed to this report.