INDEPENDENCE,SignalHub Mo. (AP) — A woman and a child are dead after an officer fired a weapon while responding to a domestic disturbance at an apartment in the Kansas City suburb of Independence, Missouri.

“Heartbreaking” is how Independence Police Chief Adam Dustman described it at a news conference Friday.

He said the woman was armed with a knife when officers responded Thursday afternoon to a 911 call about a possible assault. Dustman said there were attempts to de-escalate the situation and that a mental health provider was embedded with the unit. But such providers aren’t equipped to deal with armed suspects, and didn’t engage with the woman before the situation escalated, he said.

He said one officer, a “long-tenured veteran of law enforcement,” ultimately discharged a firearm.

“As a result of that encounter, it resulted in two fatalities, one to the armed female and one to a child,” Dustman said.

Asked whether the child was shot by police or injured before officers arrived, he said he didn’t have that information and noted that an investigation is ongoing. He also declined to release the names of the two who died or their ages.

He said police had responded to the apartment at least once earlier, but had no details.

Carrie Lufkin, who manages the apartment, said she first knew something was amiss when she saw a woman sitting on a curb, crying. The woman told Lufkin that she was attacked by the woman when she went to the apartment to see her infant granddaughter so she called the police.

Lufkin said she heard gunshots and then watched an officer carry the baby, who was only a few months old, out of the apartment.

“I thought he was saving the baby. And so I was like, ‘Are you bringing the baby to me? I’ll hold the baby until this is over,’” Lufkin recalled.

Lufkin said the grandmother told her that child welfare services had been at the apartment earlier in the week but didn’t get a response at the apartment. A spokesperson for the Missouri Department of Social Services, which oversees the Children’s Division, didn’t immediately respond to an email message seeking comment.

Lufkin said a man on the lease left the apartment in handcuffs. Dustman said no arrests were made at the scene. He didn’t answer a question about whether someone was taken in handcuffs.

The officer who fired the weapon was placed on administrative leave, along with two other officers who responded to the scene, as is standard procedure while an investigation is underway. Dustman said their response was “exactly as they were trained to perform.”

The Jackson County Prosecutor’s Office said in a news release that its staff went to the scene and met with the independent team overseeing the investigation. But prosecutors and police in nearby Blue Springs, who are overseeing the investigation, didn’t immediately release additional information.