Witnesses Kelly Lay and Mira Sytsma recount the terrifying moments when a man opened fired at Portland-area mall, killing two before turning the gun on himself.

Updated at 7:58 a.m. ET: A masked gunman killed two people and seriously injured another in a Portland, Ore., mall Tuesday, sending Christmas shoppers and people waiting in line to see Santa Claus running for cover.

The gunman, described as an adult male, took his own life after spraying bullets around the mall, said Lt. James Rhodes, of the Clackamas County Sheriff's Office.

The shooting happened around 3:20 p.m. local time (6:20 p.m. ET) in the food court near Macy's, triggering panic among an estimated 10,000 shoppers at the Clackamas Town Center.

Several witnesses reported hearing the suspect announce, "I am the shooter," before he began firing.

"All of a sudden, I just heard a series of gunshots… boom, boom, boom, boom, boom… whatever the shooter was shooting at, they continued to shoot," shopper Bill Hoff told NBC station KGW.

A young woman, Kristina Shevchenko, was rushed to the hospital in "critical" condition, according to a family statement. After surgery, the 15-year-old was upgraded to "stable" condition.

Police agencies were able to "basically hunt down, find this guy" in record time, Sheriff Craig Roberts told NBC station KGW.

When the shooting began, people in line to get their photos taken with Santa immediately dove for cover, KGW reported.

A woman who answered the phone at a Chipotle restaurant in the mall Tuesday told NBC News that someone ran in and yelled, "It's a shooting, it's a shooting."

Clackamas County Sheriff Craig Roberts discusses the gunman who opened fire at a Portland-area mall, saying it "looked to be a random shooting."

She said employees shut the doors, and the mall was crawling with police.

Macy's employee Mariah Saldana told KGW that she was sitting by the door "watching what was going on and then some guy just ran by in a white mask and an assault rifle and then I look out because I hear a few shots and he's … and he’s sitting there and he's pointing the gun at some people."

"We ran to the fitting room, grabbed some people then ran out to the back exit to get out of there," she added.

"It was just shot after shot after shot. It was terrible. It was like a massacre," witness Kira Rowland told the station.

Pedro Garcia, 24, told the Oregonian that he had been on his way to the Panera Bread Co. to buy sandwiches when he heard at least six shots.

"I could smell the gunpowder," Garcia said. "That's what pretty much what made me run."

NBC's Mike Taibbi reports from Clackamas, Oregon, where a gunman opened fire inside a mall, killing two people and badly injuring a third before he killed himself.

Rhodes said some people had hidden in break rooms and bathrooms in the mall and that teams of police were working their way through the mall to bring them out.

He said the number of people in the area making calls had overwhelmed cellphone towers.

Rhodes said police do not believe there was a second shooter.

News reporters interviewed the mall Santa, who promised he would return to Clackamas Town Center on Wednesday.

Roberts said their thoughts and prayers went out to the victims and their families.

"For all of us, the mall is supposed to be a place we can all take our families, feel comfortable, this is the holidays … these things are never supposed to happen. We have a young lady at the hospital fighting for her life right now," he said.

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