I think they were hit by over 50 rounds between them, some researchers have said 50 odd each!....they had trouble embalming them becasue they kept leaking, It was close range and brutal, loads of rounds went though the side window at head height, so the metalwork holes are only a part of it:
"Each of us six officers had a shotgun and an automatic rifle and pistols. We opened fire with the automatic rifles. They were emptied before the car got even with us. Then we used shotguns. There was smoke coming from the car, and it looked like it was on fire. After shooting the shotguns, we emptied the pistols at the car, which had passed us and ran into a ditch about 50 yards on down the road. It almost turned over. We kept shooting at the car even after it stopped. We weren’t taking any chances.”
This clip is not 100% accutrate with the desciption of events by those involved but it gives a good impression of what happened...