The deadly incident unfolded around 7:30 p.m. Monday at the Sierra Madre Villa Metro station, where a gunman shot someone in the shoulder and took off running. The condition of that victim has not been released.
Moments later, Officer Bryan Vasquez spotted the suspect nearby. The five-year veteran of the Pasadena Police Department exchanged gunfire with the suspect, who was hit and died at the scene.
Some residents in the area said they heard up to 15-20 gunshots. Bullet holes were left in a brick wall in the neighborhood.
Officer Vasquez was also shot and rushed to the hospital for critical surgery. Hours later, officials said he was out of surgery and in "stable but guarded condition."
"They run into this knowing what the potential outcome is, ," said Chief Gene Harris. "You end up with circumstances like this from time to time, but it's nothing short of heroic when the officers come out here at night time, in the dark, and chase people who might otherwise want to harm folks."
Police officer shot, suspect killed in Pasadena gun battle
Meanwhile, family members identified the suspect as 32-year-old Malcom Buchanan and said he was struggling with mental health issues.
Rose Webster, who identified herself as the suspect's grandmother, spoke to Eyewitness News at the scene. She believes her grandson may have been off his medication.
"Right now, I'm in shock and I know that I'm going to be feeling it soon," Webster said.
"I love my grandson and he wanted to live... I just left his apartment. It was so neat and nice in there, calm spirit. But I don't know what happened."
Police have not officially identified the suspect.
Footage from the scene showed the suspect's body on the sidewalk as the area was blocked off amid an investigation. A gun and an officer's bulletproof vest was near the suspect.
No additional details about what led up to the shootings were available. An investigation is ongoing.