A cement truck driver was airlifted to the hospital in serious condition after the vehicle rolled over in South St. Vrain Canyon Thursday afternoon.

The driver had to be extricated from the vehicle, the Boulder County Sheriff's Office said. The truck did have cement in it when it flipped onto its side.

It happened near mile marker 28 at around 1:30 p.m. The rollover prompted authorities to close Highway 7 in both directions from Lyons to the Peak to Peak Highway.

There's no word yet on when the highway will reopen.

What caused the rollover is under investigation.