HARRISBURG, Pa. (AP) -- Twenty-two people have died in the past week in western Pennsylvania from a suspected overdose of a mix of heroin and the powerful narcotic fentanyl, Attorney General Kathleen Kane said Monday. Kane's tally came a day after Allegheny County's medical examiner said 17 people died over the past week and called the deaths a "major public health crisis." Kane said the heroin is believed to be in bags stamped with the words Theraflu, Bud Ice, and Income Tax. Bags with those stamps have been found by narcotics agents in Allegheny, Westmoreland, Armstrong, Butler, Lawrence and Beaver counties, she said. She also warned that the stamped bags could spread to other areas and that police and hospital and health officials are being asked to be on the lookout for them. Fentanyl is a synthetic morphine substitute that is roughly 100 times more powerful than morphine. It resembles heroin, though it is much more potent, and it has been blamed for dozens of deaths around the U.S. Allegheny County Medical Examiner Karl Williams told the Pittsburgh Post-Gazette on Sunday that he did not know whether the substance believed to be involved in the overdoses was prescription fentanyl or "something synthesized by some clever chemists." Each of the people examined by Williams' office who died in the rash of overdoses had a known history of drug abuse, particularly heroin, Williams said.