Off-Duty Detective Wounds Robbery Suspect During Chase : Crime: Police say one of two fleeing men was shot when he headed toward pursuing citizens with an upraised butcher knife.

An off-duty police detective helped a group of citizens chase a pair of robbers in Woodland Hills and shot one of the suspects when he tried to attack his pursuers with a butcher knife, Los Angeles police reported Friday.

“He fired to stop him from stabbing anyone,” said Lt. William Hall, supervisor of the department’s officer-involved shooting team.

Police said Edward Lujan, 27, was in critical condition at Northridge Hospital Medical Center and will be arrested on suspicion of robbery and assault when his condition permits. Mario Carello, 25, the second man who was chased by the citizens, was arrested on suspicion of robbery and assault.

Detective Ted Ball of the robbery-homicide division was off duty and taking his wife to dinner about 5:30 p.m. Thursday when he saw two men assaulting and robbing a woman in a car in the parking lot of a drugstore in the 21900 block of Ventura Boulevard, police said.

Ball, 39, and several other bystanders who saw the attack began to chase the men. At one point, one of the men turned and threw two wallets taken from the woman at their pursuers.

“They gave up the property in hopes the people would leave them alone,” Hall said.

But the chase continued and the suspects split up after running about a block to Clarendon Street. One of the men got away. But Ball followed the other, later identified as Lujan, who ran to the rear of an apartment building, police said.

Ball identified himself as a police officer and fired a shot when he saw Lujan had a butcher knife in his hand and he feared that the pursuers were in danger, Hall said. The shot missed, and Lujan ran toward an alley next to the apartment building.

Lujan was headed toward a small group of people who had chased him and raised the knife, Hall said. Ball fired another shot, which struck Lujan in the back.

“The first shot missed,” Hall said. “But it made the guy change directions. He went the other way and he actually raised the knife as he got close” to the other pursuers.

“He was about to stab them” when Ball shot, Hall said. “Afterward, when we talked to these people, they said they thought they were about to be attacked.”

After the shooting, police went to a nearby home where Lujan had been staying with friends. Carello was found there and arrested, police said.

The 50-year-old woman who had been robbed was treated for a bruise on her head, police said.