The crash involving seven vehicles, including the deputy's patrol car, happened on Highway 6 N at FM 529 in front of a Home Depot.
According to an update from officials, a driver said that his SUV had a mechanical failure, causing it to slam into the back of a vehicle. That vehicle then veered to the right.
The SUV also hit the back of the deputy's patrol Tahoe that was in the left turn lane, triggering a chain reaction with other cars in that same lane.
The driver's SUV caught fire, burning the deputy's unit as well.
Three people, including the deputy, were taken by ambulance to the hospital with minor injuries.
The crash initially caused shutdowns that have since cleared.
ABC13 is told the area has seen multiple accidents.