Updated

Police say a one-armed woman tried to rob a Pennsylvania bank.

East McKeesport police say 51-year-old Wanda Irvin entered the Key Bank branch about 4 p.m. Tuesday armed with a knife and demanded money. When the teller refused, police say Irvin ran out of the bank and drove away.

Police say a witness got Irvin's license plate, which they tracked to her home where they found a knife in her purse.

Police say Irvin acknowledged the robbery attempt and repeatedly told them, "I don't know why I did it" — a remark she repeated to WPXI-TV outside the police station.

Online court records showed she is in custody at the Allegheny County jail on charges of robbery, possessing an instrument of crime and simple assault.