Authorities say a tanker truck veered off the Kansas Turnpike south of Wichita and crashed, causing a powerful explosion and killing both people onboard.

The Kansas Highway Patrol says a witness saw the truck hit a guardrail before losing control Saturday afternoon about a mile north of the Belle Plaine service area.

The Wichita Eagle reports that authorities say the male driver and female co-driver were from Oklahoma. They did not release the victims’ names.

Master Trooper Joel Powers says a motorist started toward the truck to help but the truck was already burning and it was too late. He says the truck exploded about 10 minutes after he arrived.