An off-duty officer with the Chicago (IL) Police Department fatally shot a suspect who he said was trying to rob him on Thursday morning. Police said a second suspect is in custody, according to ABC News.

The officer was in his car when police said two unidentified teens—16 and 17 years old—displayed a gun and demanded he hand over his wallet.

The officer complied, but one of the teens discovered the officer's badge. A struggle ensued and shots were fired.

One teen was pronounced dead at a nearby hospital. The other fled the scene but was later taken into custody by police.

"They see the police star, the offender with a weapon points the weapon at our officer and tells him not to move," said Chicago Police Deputy Chief Al Nagode. "The officer, knowing that he is armed, is forced to pull out his weapon and he fires at the individual armed with a gun, striking that individual."