This takes place within a fraction of a second. As the air expands from the heat, a loud bang is heard, which is, of course, thunder. Even when the storm seems to be far away, a bolt can strike miles away from the main storm. Often there are still charges building up in the same area of the cloud where lightning just came from, and since there is a fresh path of ionized air available, the lightning strikes again. This is the flickering you may have noticed sometimes.
Lightning indeed can strike several times in rapid succession.
The resulting lighting bolt. The negative stepped leader from the cloud has met a positive leader from the ground Lightning is very dangerous. Be careful when photographing lightning.