Interestingly worded title - did the car drive itself into the crowd? No, right? Then why would they word it like that?
Anyway, more evidence to support the fact that cars are far too efficient as weapons to be granted as much free rein as they are today. Bollards save lives, implement them liberally throughout any areas with pedestrians.
A group of what? There are people that heard about the attacks and are immitating them. Cars are easy to obtain weapons, sadly.