A motorcyclist speeding and driving recklessly on westbound Interstate Highway 580 in Livermore was killed in a crash involving a big rig Thursday morning, authorities said.

The California Highway Patrol said the crash was reported at about 5:40 a.m. in the westbound lanes of Highway 580 at North Livermore Avenue. CHP spokesman Officer Tyler Hahn said a motorcyclist was traveling at a high rate of speed between 80 and 100 mph and cutting in between vehicles before being run over by the big rig. 

"At some point, the motorcycle rider either hit a big rig and went down, clipped another vehicle and went down, and potentially got run over by a different truck and tractor combination," said Hahn.

Hahn said the motorcyclist was a man in his 40s.

As of 7 a.m. four westbound lanes were closed, with only the far left lane open. Westbound commute traffic on 580 appeared to be backed up to Tracy and Highway 205.

This is a breaking news update. More information to be added as available.