The suspect was identified as Kendrec Lavelle McDade of Azusa. McDade's family said he was 19 years old.
The shooting happened about 11 p.m. Saturday near Orange Grove Boulevard and Sunset Avenue. Police were responding to an armed robbery call. The caller told police two men had robbed him at gunpoint and fled the scene.
According to police, two officers attempted to detain McDade. They said the officers opened fire as the teen was reaching for his waistband because they believed he was going for a gun. No weapon was found.
McDade was transported to a hospital, where he succumbed to his wounds.
The officers were not injured during the incident.
The family attorney as well as community activists said they have serious questions about the deadly shooting.
"You don't have to be a mathematician to know that it doesn't add up and we want some speedy answers," attorney Caree Harper said. "It shouldn't be open season on young black men getting killed that are unarmed."
The Pasadena Police Department said it's working to get the answers. It said it has asked the Office of Independent Review group to investigate the shooting, as well as the Los Angeles County District Attorney's Office's officer-involved shooting team.
"We're taking this very serious," said Pasadena police Lt. Phlunte Riddle. "We want to make that it's completely transparent, that we have reached out to not only our detectives, the D.A., but an independent source so that we assure our community that we're going to do everything we can to make sure they have all viable information."
The victim's mother, Anya Slaughter, said her son was a football standout at Azuza High School and dreamed of becoming an attorney.
'I'm very devastated. Kendrec was my world, he was a good kid," Slaughter said. "I just want to make sure justice is served for my son."
The second suspect, a 17-year-old Pasadena boy, was arrested in the immediate area without incident. He faces felony counts of burglary and grand theft.
The family of Kendrec McDade has set up a memorial fund at Chase: Bank Account No. 452408953.