It was wrong for the South Korean coastguard to fire at Chinese boats. This might sparkle up a war between the South Korean and the Chinese. Whatever issue they had, i think there was a better way for them to stop the Chinese boats than firing at them. That was not a good decision.
China has the fiercest, largest military in the whole world. The choice of the South Korean coast guard to fire at Chinese boats is a daring one, but one that may have dire consequences. China is not exactly known for being docile and reasonable, and they sometimes get involved in petty disputes, so this could indeed lead to war.
There are two sides to every story. In this particular story, the Chinese boats were illegally fishing in South Korean waters. South Korea has made it a point to say that they were going to start aggressively pursuing these illegal boats. China and South Korea will work this issue out, as it seems like it was just a one time incident and there were no casualties.
No, this will not lead to a war, but there will be consequences. Countries cannot just fire weapons at each other and think nothing will happen. At the same time, it should not be enough for two countries to declare war on each other. There are two many negatives associated with war.