At least two people are dead and 18 others injured after a Greyhound bus carrying about 40 passengers flipped over on its side in south San Jose, Calif., causing miles of traffic backup, according to the California Highway Patrol. The incident occurred at around 6:40 a.m., as the bus was travelling north on Highway 101 near Highway 85, reported CW's Los Angeles Affiliate KTLA 5.

Greyhound's bus tracker indicated that the bus left Los Angeles just before midnight. and had scheduled stops in California including San Jose, San Francisco and Oakland. 

The two who died were identified as women, but their names were withheld. It was later revealed that they died after they were ejected from the bus as a result of the impact experienced during the crash.

Those who were injured were treated for various injuries, with four of them being transported to area hospitals with major to moderate injuries and boy of undetermined age being taken to a hospital as a precaution, reported ABC 7 California. The remainder of those injured, including the driver, were treated on-site.

Aerial footage of the scene showed the damaged bus on its side, blocking several lanes, with debris spilled onto the roadway. More than a dozen patrol vehicles and fire trucks swarmed the scene, urging passing motorists to steer clear of the area.

The crash caused traffic to be backed up for miles, in what had already been a slow morning commute due to rain, according to FOX News.

It's not clear what caused the crash, but the passengers, who were awake at the time, report that the bus was swerving back and forth prior to the crash, possibly indicating that the bus driver was asleep.