Witnesses to the stabbings in a Sydney, Australia, mall on Saturday described a scene of terror as shoppers fled from the knife-wielding man or huddled in stores as panic spread through the shopping center.

Video taken inside the mall showed a man in dark shorts and a dark shirt running at people with a knife. Some of those fleeing from him appeared to be adults holding the hands of young children. One man confronted the attacker on an escalator to try to stop him.

Andrew Reid, a lifeguard, told Sky News Australia that he had been on an errand at Myer, a retailer, when shoppers were told to evacuate. Many of the stores were in lockdown, Mr. Reid said, but after seeing people lying bleeding on the floor, he went to administer first aid.

“There was so much blood,” he said, adding that he had treated one woman who was wounded in her back, and that others trying to help had used cotton T-shirts and other pieces of clothing to stem the bleeding. Another woman he treated had been stabbed in the chest, he said. “She was in a pretty bad way.”

A senior police officer who had been nearby confronted the attacker, and she then fatally shot him, according the police. One witness told the Australian national broadcaster, ABC, that he had heard screaming and followed the police officer who was chasing after the man, and then saw her shoot him.

“If she didn’t shoot him, he would have kept going,” the man said, adding that the officer had administered CPR to the attacker afterward.

One woman who had been at the shopping center complex on Saturday told the national broadcaster that she had been at the gym and then hid in a store after hearing gunshots.

“I thought I was going to die,” she said through tears, adding. “I saw a woman lying on the floor in the Chanel.”

Other witnesses described seeing emergency workers treating a baby with stab wounds. Many said they felt disbelief at the sudden attack on people simply going about their lives on a weekend afternoon.

“It was harrowing,” Brendan Blomeley, who was in the mall with his 13-year-old daughter and 11-year-old son, told the national broadcaster. But he praised the police for their response to the attack.