Allegheny County Police Superintendent Christopher Kerns said the officers were responding to a call about a man experiencing a mental health crisis.
When they tried to make contact, the man walked away, Kerns said.
Family members reportedly warned the officers the man was possibly armed with a firearm.
When the officers caught up with the subject, he opened fire on them, according to Kerns.
Both were hit. One was mortally wounded and died at a local hospital. The wounded officer was flown to a Pittsburgh trauma center in critical condition. The officer is stable, according to Kerns.