For 1 car battery to catch a car on fire----it would take a little time to get to the gas tank and then cause an explosion and then set other cars on fire possibly.
For 5 cars to instantly all have 5 car battery explosions is IMPOSSIBLE...........beyond IMPOSSIBLE
So it was a "WARNING" from someone or some thing.....or a blast from space, similar to 911
The 1 way you know it was an attack, is how these that drove the cars say they have zero interest in investigating the attack