I only remember the ending:
A woman, her boyfriend and 2 kids are on a van. The vehicle is rigged with explosives and they are demanding payment (I think is was ransom for the children). One of the two is holding a button, connected to the detonator.
Another man is outside, on the road, running towards the van (not sure if he was law enforcement or a relative of the kids). Something happens and the couple decides to blow up the van. The button is pushed and the van explodes, with the guy, the woman, the children and all.
The man on the road stops, gets on he's knees and cries.
It's an old movie. But I can't remember how old.