Virginia Beach police have placed four officers on administrative leave while they investigate the weekend fatal shooting of a couple inside a vehicle as their 4-month-old son sat in a car seat in the back of a car.

The baby was not hurt, Virginia Beach Police Chief Jim Cervera said at a news conference Tuesday afternoon.

Cervera said India Kager of College Park, Md., and Angelo Perry of Virginia Beach died of their wounds. Four officers fired 30 rounds at the pair Saturday after, they say, Perry fired at them. Police said one of the four rounds Perry fired struck an officer’s shirt but no one was wounded.

The entire encounter — from the time officers approached the couple’s car to the end of the shooting — lasted less than 15 seconds, Cervera said.

Cervera said that police officers in a special operations unit had been doing surveillance on Perry, who was a person of interest in a homicide. He said officers learned that Perry — who according to court records was sentenced to 13 years in prison in 2001 for a malicious wounding case involving a firearm— was planning to commit a violent crime.

Cervera would not give further details about the homicide that Perry had been linked to or about the crime that officers thought he was planning to commit.

“He was a person of interest in a homicide case. And we did know that he was armed — we knew that he was heavily armed. We did have credible information that he was going to commit a violent act in our city,” Cervera said.

Kager was sitting in the driver’s seat beside Perry when she was fatally shot. In an interview, Kager’s mother, Gina N. Best, a mortgage broker from Columbia, Md., said she does not believe her daughter was the focus of any law enforcement investigation.

“It was very clear to me that India was not part of the police investigation based on the responses I got from police. She had nothing to do with it. She was totally innocent,” Best said. “Did they find any weapons on India? Did she pose a threat? Why did [police] shoot into a car with a baby and woman who had nothing to do with their investigation?”

Police declined to discuss the investigation Tuesday evening.

At a news conference earlier in the day, Cervera said that a group of officers following Perry in unmarked vehicles on Saturday observed him in a car with Kager. She was driving erratically, Cervera said.

When Kager parked at a 7-Eleven, the officers also parked and approached the car. They were wearing ballistic vests marked “police,” Cervera said. Perry shot at them almost immediately, using a 9mm pistol. Cervera said Perry also had a semiautomatic weapon in a bag at his feet.

Cervera said officers did not see the baby in the back seat until after the shooting and paramedics were attempting to save Kager and Perry. At that point, officers went to a nearby Wal-Mart to buy food and diapers for the baby until Child Protective Services could take care of him, Cervera said.

“Virginia Beach Police Department and our officers believe in the sanctity of life. We do everything we can to mitigate violent conflict,” Cervera said.

Cervera would not name the four officers who fired at the couple, saying that someone had made a threat against the police department Monday and he wanted to protect the officers’ safety.

He said that all four are performing administrative duties while the deaths of Kager and Perry are under investigation. The four officers are white, and Kager and Perry were black, he said.

On Facebook, Best posted photographs of her daughter clad in a military uniform and messages including, “SHE DIDN’T HAVE TO DIE” and “WE . . . NEED . . . ANSWERS . . . NOW!!!”

“Our hearts are BROKEN!!” she wrote Tuesday, addressing her daughter as “my radiant flower.”

“She posed NO THREAT to the officers that killed her. THIS HURTS BEYOND WORDS.”

Best added the hashtags “#NavyVeteran” and “#BlackLivesMatter,” references to Kager’s military service and the nationwide activist movement protesting police brutality against black citizens.

Best said her daughter’s death at the hands of law enforcement is especially tragic because her family counts among itself two retired D.C. police officers: Kager’s father and grandfather, both named Richard Kager.

Best said that Kager and her two sons — an infant and a 4-year-old — lived with her father and grandfather at their College Park home.

She said her daughter, a former Navy service member, worked for the U.S. Postal Service as a letter carrier. A graduate of the Duke Ellington School of the Arts in the District, Kager played multiple instruments.

“India was very loving and introspective and calm in her demeanor,” Best said. “She was very poised. She was definitely not something that would you would characterize as ‘unsavory.’ ”

Best said she had not met Perry. “I’ve heard his name before, but he’s a complete enigma,” she said.

Relatives of Perry could not be reached.

An earlier version of this story incorrectly said there was a 6-month-old baby in the car. The baby was 4-months-old.

Magda Jean-Louis and Julie Tate contributed to this report.