HOUSTON (AP) -- A tanker truck exploded into a huge fireball Tuesday afternoon after colliding with at least two vehicles on one of Houston's busiest freeways.

At least five people were taken to a hospital but none of the injuries was believed to be life threatening, fire department spokesman Jack Williams said.

The wreck halted traffic on Interstate 610 just south of U.S. 59 on Houston's southwest side. It occurred on the northbound side of the freeway, known as the Loop in Houston, but traffic in both directions of the highway, at least eight lanes wide at that point near Houston's Galleria, was blocked. The southbound lanes of the freeway were reopened late Tuesday afternoon and officials expected to do the same for the northbound lanes sometime during the evening.

The tanker truck was on its side burning as firefighters sprayed it with foam. Clouds of black smoke billowed high into the sky and it took nearly an hour to put the blaze out. Contents of the truck were not immediately known, but a fire department spokesman said it was believed to be gasoline.