OAKLAND, Calif. -- A U.S. Postal careened into two other vehicles on busy Highway 880 in downtown Oakland early Monday, exploding into a massive fireball that scorched the freeway and triggered a massive traffic backup, authorities said.

CHP Sgt. Sherri Jones said the crash occurred at around 2:20 a.m. when the empty postal truck could not avoid a vehicle that had slowed to assist another driver whose car had stalled

The postal truck jackknifed and its fuel tank ruptured. The fuel was ignited by sparks and the truck exploded into a fireball. Fortunately, the truck driver was able to escape without injuries, Jones said. However, the driver of one of the vehicles was injured in the crash and taken to the hospital with minor to moderate injuries, Jones added.

A dog in the woman’s car was killed.

The crash blocked all northbound lanes of Highway 880 for about three hours, according to the CHP. Two lanes were reopened as of about 5:20 a.m., but the other lanes were closed until 8:30 a.m. while crews clear the big rig from the roadway,

The lingering effects of the crash created a commute nightmare on the busy freeway with traffic backed up for miles.