The investigation into a deadly construction crane collapse at a Google building in Seattle now involves five companies, according to the state Department of Labor and Industries (L&I).

Video from a car's dashcam shows the driver approaching the scene from the Interstate Highway, stopping for a red light.  At that point, the crane - on the right side of the screen - comes crashing down from behind a building and onto the street.  Two ironworkers on the crane were killed, and two people in cars on the ground were crushed. 

The investigation involving the five construction companies on the building site is just getting underway.  But several observers have speculated that the pins holding the big thing together had been removed prematurely. 

"Once we have a conclusion, we will meet with the companies involved, we will spell out what we found, we'll let them know if we found any safety violations, if they're being cited or penalized, and once we do that, that information is public for everyone to see what happened," said Tim Church, a spokesman with the Washington State Department of Labor and Industries.