At least two people were killed and three others injured Friday after an 18-wheeler exploded following a crash on Interstate 35W in Denton, Texas, authorities said.

The multi-vehicle crash occurred in the northbound lanes, the Denton Police Department said.

The cause of the crash is unknown.

All lanes in both directions are closed. Denton is about 45 miles from Dallas.

This is a developing story, check back for updates.