(Reuters) - A pileup of 80 to 100 vehicles on a foggy Texas interstate on Thursday injured at least 51 people, eight critically, officials said.

The pileup in the eastbound lane of Interstate 10 near Beaumont shut down the highway in both directions.

It came as millions of Americans are on the road, heading to Thanksgiving holiday feasts.

The cause was unknown but the area had heavy fog, a dispatcher for the Texas Department of Public Safety said.

Denise Richter, a spokeswoman for Acadian Ambulance Service in the area, said her company had transported 51 people to five hospitals. Eight of them were critically injured.

She said other ambulance services had been at the scene. Richter and did not know the total number hurt.

(Reporting by Ian Simpson in Wasington; Editing by Sandra Maler)