Did another heist mission last night, soon as we finished the mission we spawned at a large intersection and a huge UFO appeared clipping though the road, it then went invisible and seemed to cause cars and buses to start flying and exploding all over the place.
Then me and my m8 got stuck in invisible boxes and other players started spawning in similar boxes at the same place on the map, then the fire came.
I remember playing DayZ when hackers would join maps and it could be fun, raining cows etc etc but GTA hackers just seem intent on clearing servers/maps of people, which is a shame...