Two pizza shop employees got into a fight Friday morning that ended with one co-worker stabbing the other, Butler police said.

Stephen L. Critchlow, 22, of Butler Township was arrested on felony assault charges following the altercation at Vocelli Pizza on West Cunningham Street.

Police suspect Critchlow stabbed his boss, William McCullough, 41, of Penn Township, who was treated at Butler Memorial Hospital. He was later charged with misdemeanor assault in the fight.

Officers were called for a reported fight shortly after 11 a.m. in front of the pizza shop on the city's West End. Police found the suspect and alleged victim as well as two other employees.

McCullough, the general manager, told officers that Critchlow came to the store to pick up his paycheck, according to court documents. The two exchanged words after which McCullough refused to give the defendant his paycheck.

After the victim eventually turned over the paycheck, police said, the suspect threw the store keys at him. Critchlow was ordered out of the store. But before leaving, documents said, he threatened McCullough.

The manager followed Critchlow outside and the two got into a fight during which the defendant allegedly stabbed McCullough in the left side of his back with a 3-inch folding knife.

The suspect, however, blamed his boss and said he only acted in self-defense.

“Critchlow stated that McCullough attacked him and he was very sorry for stabbing him,” according to a police affidavit.

Police noted that the defendant suffered facial injures from being punched by McCullough.

Two other employees, including the assistant manager, corroborated McCullough's account of what happened.

One of the co-workers tried to stop the fight and later pried the knife from Critchlow's hand, documents said. The defendant's wife, who was there, also helped take the knife from her husband's hand.

McCullough received “several sutures” for his injury, police said.

District Judge Sue Haggerty arraigned Critchlow on charges of aggravated assault and disorderly conduct. He was placed in the Butler County Prison on $10,000 bail following arraignment.

McCullough is charged with simple assault and disorderly conduct. Police said he will receive those charges in the mail.