MINNEAPOLIS — The partner of a Minneapolis police officer who fatally shot an unarmed woman who had called 911 to report a possible crime testified Thursday that he heard a thump on the officers' squad car right before the shooting and feared a possible ambush.

Officer Matthew Harrity's testimony echoed a key claim by attorneys for Mohamed Noor, who fired a single shot at Justine Ruszczyk Damond as she approached the officers' squad car on July 15, 2017.

Damond had placed two 911 calls that night to report a possible sexual assault in the alley behind her home. Struck in the abdomen, the 40-year-old dual citizen of the U.S. and Australia quickly bled to death in an incident that sparked anger and disbelief in both countries.

Prosecutors have questioned the defense narrative of a thump on the squad car, saying investigators found no forensic evidence that Damond touched it. They've also questioned the timing of the claim, saying Harrity first mentioned it days after the shooting and after investigators raised the possibility.

Noor never talked to investigators and it isn't clear whether he will testify.

Justine Damond Stephen Govel Photography

On Thursday, Harrity described a tense scene, with he and Noor rolling down the dark alley with headlights off, using a spotlight to search for any evidence of a woman in trouble. Harrity, who was driving, said that at one point he took a safety off his holster, but that when they neared the end of the alley without finding anything, he thought he had replaced it.

Harrity — wearing his uniform and appearing composed on the stand — testified that he then had a "weird feeling" to his left but couldn't make out what it was.

"At this time, I hear something hit the car and I also hear some sort of murmur," he said. He immediately drew his gun and held it to his ribs pointing downward, he said.

Prosecutor Amy Sweasy asked Harrity whether he always pulled his gun when startled. He said it depends.

"In this situation, with the thump and being startled, I went straight to, 'This could be an ambush,'" Harrity answered. He added: "My first thought is, I'm going to make sure whatever it was is not a threat to me."

Harrity said that as he tried to make sense of what was happening, he heard a pop and looked over to see that Noor had fired across him and through the driver's side window.

Neither officer had their body cameras running at that point, something Harrity blamed on what he called a vague policy that didn't require it. Both men switched them on afterward, and a portion of Harrity's was played Thursday.

It shows efforts by the two men to save Damond with CPR. Damond's labored breathing is heard, with Harrity saying, "Stay with me, stay with me, stay breathing." He also is heard addressing his partner: "Noor, breathe, just breathe."

At one point, as Harrity steps away to get medical supplies, he cautions Noor to slow down the CPR, and reassures Noor that an ambulance is coming.

A medical examiner testified earlier that Damond was hit in a key artery and lost so much blood so quickly that even faster medical care might not have saved her.

Former Minneapolis Police officer Mohamed Noor arrives with his lawyers for the beginning of his trial on April 1, 2019 in Minneapolis. Stephen Maturen / Getty Images file

Damond was white. Noor, 33, is a Somali American whose hire two years before the shooting was celebrated by Minneapolis leaders as a sign of a diversifying police force in a city with a large population of Somali immigrants.

Much of the prosecution's early case focused on the handling of the crime scene by police and state Bureau of Criminal Apprehension agents, including possible missteps. They also highlighted officers turning their body cameras on and off repeatedly after the shooting.