DENVER -- A man critically injured in a shootout with Denver police was living in a halfway house while serving an 18-year sentence for aggravated robbery and assault, authorities said Thursday.

Phuong Dang, 26, was in serious condition at a Denver hospital.

Dang was masked and armed with a shotgun when he tried rob a Vietnamese restaurant on Wednesday. He got into a shootout with two undercover officers who just happened to be eating lunch there.

A witness next to the Ha Noi restaurant said that the chef told her the gunman entered the restaurant through the back door and held the shotgun up to his head. A waitress in the back kitchen then ran through the restaurant and out the front door, alerting officers that something was wrong.

The officers opened fire on the gunman.

"It wasn't a situation where they could say, 'Stop! Police!' because it could turn into a hostage situation," said Denver Police Chief Gerald Whitman.

It is not clear who shot first, but during the exchange, three family members were hit.

One of the family members, a mother, was still in a hospital Thursday night.

Police speaking to the media Thursday night said they believe the mother had been hit in the side while the other members were hit in the ankle and grazed on the leg.

Denver police said the two officers fired 12 shots at the suspect. Police believe four of the bullets went through Dang and hit the family members sitting nearby.

Police said Dang was carrying a shotgun and fired off one round very close to the table where the officers were sitting. The blast broke the table, scattering glass all over the restaurant.

One shard went into an officer's eye, forcing him to go to a hospital. The officer was later released.

"If this bad guy had raised the shotgun a little bit higher, one of the officers would've definitely taken the full round," Whitman said.

Those At Nearby Shops Heard Shooting

Kim Oanh Nguyen, a hairstylist next door to the restaurant, heard the multiple gunshots and ran outside of the salon to see what was going on.

"During the shooting, the people who were inside the restaurant ran out. They ran into the parking lot and were hiding behind cars and ducking from the gunshots," she said.

"The customers inside were going, 'Why are you running outside during the gunshots? You should be back here. And lock the door,'" said her boss, salon owner Thao Nguyen.

Once she realized that the shooting continued, Kim Oanh Nguyen ran back to the salon and closed the door -- where she and the customers remained for three hours. She said she was shaking all night, thinking of what happened.

Dang Had Violent History

Dang was released from prison October 2006 and has been living in a halfway house as what the Department of Corrections calls a "transitional inmate." He had served eight years of his 18-year sentence but was still under the control of the DOC.

Police are trying to find out if he may be connected to other armed robberies in the past month or two.

Business owners said that they normally don't see this type of violence in the predominantly Vietnamese area, but realize that the gunman could have easily targeted them.

"I'm sure if our back door was open and he felt like coming in, it could have been our salon," said Thao Nguyen.

During the course of the day, several of the restaurant's regular customers stopped by to check on the staff. The restaurant is a favorite hangout with a group of Vietnam War veterans.

"This is my favorite restaurant. We used to be friends with these people back in the day. We always used to congregate down here and have lunch and talk war stories," said customer Gus Trujillo.

Investigators Will Determine If Police Used Appropriate Force

Investigators will study the shooting to determine if the officers acted with appropriate force in stopping the shooter.

On Thursday night Denver's police leadership said they supported the officer's actions.

"These officers did what they needed to do to save their lives," said Division Chief Dave Fisher. "They're trapped back here in a corner. And I believe that they saved a lot of lives inside of this restaurant."

"These detectives were placed in an impossible situation," Whitman said. "They performed courageously. And thankfully, they're OK."

The three injured victims told police they were supportive of the officer's actions, Whitman said.