Witnesses told responding law enforcement officers a dark-colored SUV rear-ended a motorcycle as both vehicles were traveling east on Highway 18.

Both occupants of the motorcycle were ejected off the cycle. The SUV continued east and left the scene.

The occupants of the motorcycle were transported to the Spencer Hospital by ambulance and later transported by emergency helicopter to Sioux Falls, S.D., for serious injuries.

The driver of the motorcycle was 30-year-old Brian Beck of Spencer. The passenger was 19-year-old Krystal Plagman of Marathon. Officials at Avera McKennan Hospital in Sioux Falls did not return a voice mail request for an update on the riders' conditions.

The SUV was located a short time later at the Country Villa Trailer Court just south of Spencer. Investigation by officers resulted in the arrest of 57-year-old James Prather of Spencer. He was charged with operating while intoxicated and improper passing. Other charges are pending as the investigation continues. Prather was placed in the Clay County Jail.

The Spencer Police Department was assisted by the Clay County Sheriffs Office, Iowa State Patrol, Spencer Fire Department, and Spencer Ambulance personnel.