Sheriff Dennis Smith announced Monday the department is now offering a $10,000 reward for information leading to the arrest of those responsible.
The shooting is believed to be retaliation for a drug arrest the officer made.
The money has been donated from other area law enforcement agencies and unions including the FBI and the West Central Drug Task Force.
"Officers from all around are pretty upset about it," says Smith. "There was phone calls right and left of people calling up to offer some kind of money to go towards the reward.
Those with information are asked to contact the Dunn County Sheriff's tipster line at 231-2907.