Yes. Report it so the police will go look for the 4 Hispanic men to check on them
WPP

Good lord, do you really have to ask this question?

Please report it. It is the right thing to do.

Report it! I've seen something similar and turned around to get the tag number of the fleeing driver. I got back to where the other driver was, only to watch him leaving before I could get to him. I called the police as soon as I got to a phone (pre ubiquitous cell days) and the dispatcher already knew about the incident. He also said they did not have a tag number for the driver who fled. I gave my name, address, how long I'd be in town, etc. I never heard back from them.

If you call and the police have no report, they'll have no way to contact the driver.

I would report it. The fellows in the truck may not have realized anyone else saw it and moved somewhere safer to call it in. Perhaps your reporting it could corroborate their report. Maybe nothing will come of it, but you will have done the right thing. If the van driver did this today he may do it again with more tragic results.

We went back to the intersection, hoping the truck was still there, but [b]they had left. [/b]

You know, rather than stay in place and call the cops themselves to take a report at the scene. Because then you might have to, I dunno, give your name and address.