A masked gunman opened fire at an Oregon shopping mall Tuesday. Three people, including the gunman, are dead, authorities said. Gunfire erupted at the Clackamas Town Center mall outside Portland shortly before 4 p.m. PST.

[Update 9:39 p.m.]

The gunman died of what appears to be a self-inflicted gunshot wound, Clackamas County Sheriff's Sgt. Adam Phillips said. He did not release the identity of either the shooter or the victims. Law enforcement did not fire any shots during the incident, he said.

[Update 8:40 p.m. ET]

Witness Kira Rowland told CNN's Anderson Cooper she was with her infant in the Macy's cosmetics area when the shooting broke out. She estimated she heard about 25 shots fired.

"I can't help but think that if I hadn't stopped to smell that perfume, maybe me and my baby wouldn't be here today," she said, her voice breaking.

[Update 8:35 p.m. ET]

Clackamas County Sheriff's spokesman Lt. James Rhodes said the shooter and two victims were dead and only one person was injured.

He said nearly 100 officers from several agencies were on the scene, searching the mall and controlling the crime scene.

"Where it began specifically in the mall I don't know," he said.

Rhodes asked witnesses to call or come to the sheriff's office to describe what they saw.

Cell phone service was overwhelmed by the volume of calls, he said, and asked people seeking information to be patient.

"I heard something similar to a .22 popping, probably eight times," witness Christina Fisher told CNN affiliate KOIN. She said people dropped to the floor and cooperate with one another to get to safety. She said she was about to leave through the Sears store, but then police blocked the doors.

[Update 8:28 p.m. ET] Witnesses and others near the scene were tweeting about their experiences.

[tweet https://twitter.com/bcmystery/status/278643618925924352%5D

[tweet https://twitter.com/jennahopeee/status/278644307936829440%5D

[Update 8:22 p.m. ET]

Witness Holli Bautista told CNN's Anderson Cooper she saw people ducking for cover in the mall's food court. She said she was not able to leave the mall parking lot because police were blocking the exits and that people were still locked inside the mall itself. Bautista said she heard about 10 shots fired and that several triage centers had been set up.

"I'm terrified. It's scary," she said. "... My thoughts and prayers are with anyone who's injured."

[Update 8:19 p.m. ET]

"Multiple victims" have been shot, said Public Safety Director Steve Campbell of the city of Happy Valley.

[Posted 8:11 p.m. ET]

A witness told CNN affiliate KOIN she saw a man running through the mall wearing a hockey goalie mask and carrying an assault rifle.

Clackamas County Sheriff's spokesman Lt. James Rhodes said one person was killed, and possibly more. He said the shooter had been "neutralized," but did not clarify what that means.