CHICAGO -- A Chicago police officer who recently returned from Iraq was shot and killed when several people approached him outside his family's home and tried to steal his new motorcycle, authorities said Thursday.

The officer's father -- a retired Chicago police officer -- came to his son's aid and shot two of the attackers, killing one of them late Wednesday, police said.

The slain officer has been identified as Thomas Wortham IV, according to the Cook County medical examiner's office.

He had just finished his second tour in Iraq, said Chicago Alderman Freddrenna Lyle, who knew him and his family.

"This is a tragedy. This young man survived two tours in Iraq, and came home and got murdered on the streets in front of his house that he grew up in," Lyle said. "In front of his father, it's just unbelievable."

The 30-year-old officer had been on the force for three years, according to Chicago Police Superintendent Jody Weis.

Charges are pending against the injured suspect, police spokeswoman Amina Greer said. Police were searching for two additional suspects who fled the scene after the shootings.