A search is on for the unknown gunman or gunmen who ambushed and fatally shot a 26-year-old sheriff’s deputy near Louisville, Kentucky, authorities said.

Jefferson County sheriff’s deputy Brandon Shirley was shot at about 2:30 a.m. local time Thursday while working an off-duty security job at Rockford Lane Auto Sales in Shively, Jefferson County Sheriff John Aubrey said at a news conference. Shirley was in uniform at the time, the sheriff said.

Shirley was rushed to a hospital where he died, Aubrey said.

The Louisville Metro Police Department is investigating.

Police chief Erika Shields said Shirley was “targeted” and “ambushed.”

She called the shooting “sickening” and vowed to make an arrest.

Shirley, assigned to the court security division, joined the department in 2019.

Aubrey described Shirley as courageous and well-liked.

Shirley and three other officers were recently awarded the medal of valor for assisting during a shooting at Jefferson Square Park, the sheriff said.

Forty-five law enforcement officers have been fatally wounded in the U.S. so far this year, according to FBI data.