Officers were investigating a ShotSpotter activation near Platt and 8th around 5:20 pm on Saturday.
That's when Interim Fresno Police Chief Mindy Casto says the gunman, 40-year-old Andy Morales, returned to the scene and shot the sergeant multiple times as he was working in his patrol car.
The bullets went through the door and hit the sergeant's legs.
"It was basically door to door as he pulled up to the patrol car and opened fire," Chief Casto explained.
"The suspect continued driving on. The sergeant being struck with gunfire, had the presence of mind to activate his body camera at that moment and initiate a really short pursuit."
Suspect in shooting of Fresno police officer and homicide identified
Morales then got out of his car and continued to shoot at the sergeant.
"Numerous gunshots were fired, both from the suspect, from sergeant involved, and about 49 seconds elapsed before another officer was able to arrive," Chief Casto said.
Two officers arrived and fired at Morales.
At least a dozen gunshots can be heard whizzing through the air in a video obtained by Action News.
Police say Morales was struck about seven times and died at the hospital.
Fresno police sergeant survives after being shot by murder suspect
The sergeant, who is a 21-year veteran of the force, is expected to be okay.
It was only after the shootout that officers discovered 43-year-old Mario Ternora had been killed inside of a nearby home.
"We located Mario inside with both gunshot wounds and stab wounds and a very vicious crime scene indeed," said said Chief Casto.
"We learned that Mario and Andy had been friends since childhood, and we really don't know what the conflict was on this particular day that resulted in Mario's murder at the hands of Andy."
Detectives say Morales used a knife in the attack on Ternora and that he also used an AR-15 style rifle, the same gun he used to shoot the sergeant.
"I truly believe, knowing the sergeant and knowing what what he has said to me, (shooting the suspect) was to keep this community safe as well," explained Chief Casto.
"Because the suspect that would attack a police officer isn't going to stop with a police officer."
As the sergeant continues to heal from his wounds in the hospital, his mental health and that of other officers is top of mind for both Chief Mindy Casto and Mayor Jerry Dyer.
In times of struggle, Casto says police lean on one another.
"Their peers reaching out to them and myself as well, to make sure they have what they need, and to let them know that they have the strength to get over this, to become better even, and come back to work and serve the community," Chief Casto said.
Beyond peer support, she and the mayor took time to spotlight the resources available to the department, including training to help with post traumatic stress.
"My praise also goes out to the Fresno Police Officers Association for their response. They're the ones that surround officers in time of crisis, along with the chaplain and the companion officers, all of them acted admirably in this circumstance and and that's what families do," said Mayor Jerry Dyer.
Police say the rifle Morales used was unregistered and illegal for him to possess due to his priors for weapons violations and gang activity.
They add that Morales had also been arrested on domestic violence-related charges, and for driving under the influence.
Chief Casto said drugs were found near the suspect, leading investigators to believe he could've been under the influence at the time.
However, investigators say that will be unknown until a toxicology report can be completed.
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