A gunman shot a sheriff’s deputy who is a Mississippi native Thursday afternoon in Vidalia, Louisiana, just across the Mississippi River from Natchez.

Concordia Parish Sheriff’s Office deputy Walter J. Mackel was shot by an unnamed gunman early Thursday afternoon after an armed man became engaged in a standoff with law enforcement officers, the sheriff’s office reported.

Neither the initial cause of the standoff nor how Mackel came to be shot was immediately clear.

The Natchez Democrat reported the gunman was found inside the apartment dead of an apparent gunshot wound after U.S. Marshals used teargas to enter the apartment.

Mackel was transported to the University of Mississippi Medical Center where he was undergoing surgery Thursday afternoon. Law enforcement sources said they believed his wound was serious, but not likely life-threatening. He was reportedly alert and conscious after the shooting.

Mackel is a veteran law enforcement officer in the Natchez, Mississippi, and Vidalia, Louisiana, area, having begun working after returning from service as Navy Corpsman for the U.S. Marine Corps.