The shooting unfolded in the area of Sierra Madre Villa Avenue and Foothill Boulevard, near the Hastings Village shopping center, according to a city spokesperson.
The officer was shot during the exchange of gunfire and taken to a hospital where he underwent surgery. His condition is unknown.
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.
Pasadena police said the confrontation followed an earlier shooting around 7:30 p.m. at a nearby Metro station, where a person was shot in the shoulder. The shooting victim's condition is unknown.
When a responding officer spotted the suspect, the suspect ran away. At some point, the officer and the suspect exchanged gunfire.
The name of the officer, who is a senior member of the department, has not been released.
No additional details about what led up to the shootings were available. An investigation is ongoing.