Sisters Blia Xiong and Mang Truong were driving to Lake Phalen in St. Paul for a walk a year ago when they interrupted a purse snatching and simultaneously solved a sex crime by accident.

The sisters tailed the thief in Truong's car as he ran and jumped into a getaway car. His victim chased him, too, screaming and waving her arms.

Xiong yelled at the man, finally persuading him to get out of the car and return the purse.

Xiong, 51, and Truong, 43, also caught a glimpse of the getaway driver. They identified him and the vehicle to police, who traced both to a sex crime that occurred earlier that September day in 2011.

"You solved two crimes in one day," St. Paul Chief Thomas Smith told the sisters Tuesday. "I want to thank you for that."

To underscore his gratitude, Smith gave them the St. Paul Police Chief's Award. During a ceremony at St. Paul police headquarters, he also recognized an officer who helped a suicidal man and two officers who entered a burning house.

"That day we didn't think," Xiong said. "We just do what anyone would do. You just hate to see innocent people hurting."

Truong, who is a 911 call taker at the Ramsey County Emergency Communications Center, said her training kicked into gear when she called 911 to report the crime.

"It's just a matter of being there at the right time," Truong said. "We didn't feel heroic."

Officer Mark Grundhauser received the Chief's Award for helping a suicidal man in April. Grundhauser, who was sworn in as a police officer last week, was a parking enforcement officer at the time.

He was driving across the High Bridge when he spotted an upset man with a woman on the sidewalk. He turned around and parked.

The man pounded his fists on a vehicle, shouting for it to hit him.

"You have no clue what I've seen," said the man, a combat medic who had served in Afghanistan.

"Yes, I do," Grundhauser answered, pointing to an Army pin on his uniform.

The woman, the man's girlfriend, told Grundhauser that her companion suffered from post-traumatic stress disorder.

Grundhauser, who served two tours in Iraq, spoke with the man until more police arrived.

Smith called his levelheadedness "admirable."

Sgt. Mike Whisler and officer Rod Larson were given the Life Saving Award for crawling through a burning house in January to alert sleeping residents.

The fire was started by a resident who was upset that a female guest had rejected his advances. He had piled dresser drawers on his bed, set them on fire and fled.

Whisler and Larson kicked down a door to enter the home, which was black with smoke. A man on the first floor told them four more people were asleep upstairs.

The officers crawled and pounded their flashlights on the floor to wake the residents. All of them, including a 2-year-old, escaped safely.

Smith said it was an "unbelievable act of courage."

"Instinct kicked in," Larson said.

Chao Xiong • 612-270-4708 Twitter: @ChaoStrib