If you look at this picture the van is stopped just 1 van length from his victims(the tent). There doesn't appear to be much damage to the front of the van, windshield is intact. From the picture there doesn't seem to be any reason he couldn't have backed up over them and continued to run them over.

Either he did a hell of a shitty job doing his attack, or this was some kinda passed out at the wheel drunk driving accident.

There are reports him getting out of the van. If you just ran over a bunch of Arabs would you get out? or would you stay locked inside..There doesn't appear to be any broken side window glass on the ground as if he was forced out by the mob.

The fact that he looked really sweaty and drunk/drugged makes me really wonder about this.

Here's a vid that shows the victims just behind the van to give a better perspective to the picture.