SPARTA, Wis. -

Five teenagers were injured after lit fireworks exploded inside a moving vehicle in Monroe County.

The Sparta Police Department was alerted to the incident about 4:30 a.m. Monday after the teens arrived at Mayo Clinic Health System in Sparta with burn injuries, according to a press release.

Investigators believe the teens were throwing lit fireworks from their vehicle when one went off inside.

The occupants of the vehicle were all 17-year-old males from the Sparta area.

The driver was able to drive to the hospital where all five occupants were initially treated from the explosion.

Four of the injured occupants were transferred to other medical facilities around the area by helicopter.

Sparta Police were called to assist in establishing landing zones for the helicopters.

It is unknown where the vehicle was at the time of the explosion.

Sparta Police and the Monroe County Sheriff's Department are investigating the incident.