An off-duty sergeant with the Police Department in Superior, Wis., crashed his minivan into the back of another vehicle early Friday and killed the other driver, authorities said.

The collision occurred about 1:15 a.m. in Superior in the 5200 block of E. 2nd Street, said Police Chief Nicholas Alexander.

Sgt. Gregory Swanson, 42, was booked into jail on suspicion of homicide by intoxicated use of a motor vehicle and awaits charges.

Alexander said that "it is my understanding that [Swanson] completed standardized field sobriety testing, to include a [preliminary breath test]." The chief said the Douglas County Sheriff's Office carried out the testing and has the results.

A message was left Friday morning with the Sheriff's Office requesting Swanson's preliminary blood alcohol content results.

The driver who was hit by from behind and died was a 23-year-old man from Eau Claire, Wis., Alexander said. His identity has yet to be released.

Three other people in that vehicle were taken to a nearby hospital, but the chief did not have specifics about their conditions.

"This is a sad and tragic incident," a statement from the chief read. "We wish to express our sincere sympathy to the family and friends of the deceased, and our hopes of a speedy and successful recovery for the other occupants involved."

To avoid a conflict of interest, Alexander explained, the crash is being investigated by the Douglas County Sheriff's Office and the State Patrol.

The Douglas County Attorney's Office released a statement late Friday morning that said it would request appointment of a special prosecutor should charges be filed against Swanson, explaining that "Sgt. Swanson has worked closely with the District Attorney's Office and its prosecutors on many cases over the years during his career with the department."

The Police Department has placed Swanson on administrative leave as the investigation continues. He has been with the department for 15 years.