After taking a second to wake up, I decided we should all get in the car and move farther back and call for help. We got into the car and move back a good 100 feet. I called 911, as at this point it wasn’t totally clear if the driver was out of the truck or might be in danger.
Firetrucks started showing up within maybe 20 minutes of when we called and got the fire under control. The truck ended up being filled with lumber, which appeared to have caught fire to some extent. They spent the next couple hours off-loading the lumber to another truck, log-by-log and spraying down each log.
The next day, we took a look at the truck as we left, the back end of it was totally destroyed.