1 A tanker truck carrying about 6,000 gallons (22,800 liters) of liquid petroleum gas exploded Sunday after skidding along a guard rail on a busy freeway, killing the driver, blowing the truck to bits and incinerating a car.
2 At least seven people were injured in the 9 a.m. explosion that sent a huge ball of flame into the sky, blew a hole in the road, ripped the guard rails and damaged the center divide.
3 Authorities closed the highway, the main interchange between Oakland, Berkeley and the San Francisco-Oakland Bay Bridge.
4 The truck's cab was blown over the other side of the freeway.
5 The California Highway Patrol said the cargo was a mixture of butane and liquid petroleum gas, a highly flammable liquid.
6 The driver's identity and company he worked for was not immediately known.
7 At least seven people were treated for burns, including an Oakland family of four that was driving to church in San Francisco. They fled their car, which was destroyed.

A tanker truck carrying about 6 , 000 gallons ( 22 , 800 liters ) of liquid petroleum gas exploded Sunday after skidding along a guard rail on a busy freeway , killing the driver , blowing the truck to bits and incinerating a car .
skidding along a guard rail
What caused the truck to skid?