(CNN) As an encounter between two Seattle police officers and a mother of four escalated, one of the cops yelled, "Tase her!"

The other officer replied, "I don't have a Taser," according to an audio of the police shooting.

After repeatedly yelling, "Get back," shots rang out.

Charleena Lyles, 30, a pregnant mother of four was shot and killed by police after she confronted officers with a knife on Sunday, authorities said.

Her death outraged her family and community members who decried the deadly use of force on Lyles, an African-American woman, who was expecting her fifth child.

"If worst comes to worst, you could have used a Taser instead of a gun for someone that has three kids inside the house," her brother, Domico Jones told CNN affiliate KOMO on Sunday.

On Tuesday, hundreds of demonstrators gathered for a vigil outside Lyles' apartment complex where she died Sunday. Holding signs that read #SayHerName and Black Lives Matter, they demanded justice.

"I just want justice for my cousin, you know," said Kenjenai Doucet to CNN affiliate KOMO. "They are portraying her in the news with illness, like way worse than it actually was, so I just want justice for my cousin. I think that's what my family wants too."

Officers discussed her previous police interaction

On Sunday, shortly before 10 a.m., two officers went to Lyles' address after she had called to report a burglary , police said.

"Typically, that would be a one-officer call, but there was some information in the system, officers had dealt with this particular unit, this particular caller just recently," said police Sgt. Mark Jamieson. "There was some hazard information so that prompted a second officer to respond."

Tributes are placed at a makeshift memorial for Charleena Lyles.

According to King County jail records , Lyles was arrested and charged with obstruction of a public officer and harassment of a law enforcement officer on June 5. That police report described Lyles as having "armed herself with a pair of extra long metal shears" and had been "threatening the officers." She was released conditionally June 14.

The responding officers can be heard on a dashcam audio recording released by police. They discussed the previous interaction Lyles had with law enforcement -- and the fact that she was the subject of an "officer safety caution."

"She started talking all crazy about how the officers weren't going to leave and she had a pair of scissors," one officer says.

"She got a mental caution on her?" the second officer asks.

"She got an officer safety caution on her," the first officer says.

"Okay, but no mental on her?" the second officer asks again. The first officer's reply is inaudible, but Lyles' sister told CNN affiliate KOMO that she told police Lyles had mental health issues when she was arrested earlier this month.

A burglary report

On the dashcam audio of Sunday's incident, officers can be heard greeting Lyles and asking questions about the burglary report.

Initially, the tone is calm.

She tells them she left her door unlocked while she went to the store and that while she was out her Xbox was stolen. A child is heard making noises in the background.

The officers ask Lyles if she knew who the suspect could be. She says she has no idea. They take down her contact information and confirm what was stolen.

Seconds later, a commotion is heard. A child cries and Lyles curses at the officers.

"We need help," an officer says, referring to "a woman with two knives."'

Officers say "get back" repeatedly. Shots are heard. Then the dashcam audio ends.

Jamieson said at some point after Lyles armed herself with a knife, both officers "had to fire their service weapons."

Officers performed first aid until the fire department arrived, but Lyles was declared dead at the scene, he said.

"It's a very traumatic event, absolutely," he said.

Jamieson would not say whether any children witnessed the shooting -- but said there were three children in the apartment at the time of the shooting. "They are unharmed, they are being taken care of right now," he said.

Lyles' family members blasted the police over the use of lethal force.

"How is she a f***ing threat? What's she going to do to all you police? You big f***ing men, I can take her down, I know you can," her sister, Monika Williams, told KOMO.

Officers had 'less lethal force options'

The statement provided by the Seattle police department said both officers were "equipped with less lethal force options," and that all its officers are trained in crisis intervention.

Seattle mayor Ed Murray called the incident a tragedy and said it would be "fully investigated" by a federal monitoring team.