Ouch. My sympathies and condolences to the victims and their families. It seems unclear from initial reports if this is in fact terrorism. From the Reuters report:
Fueled by easy access to explosives, China has seen bombings linked to disgruntled workers, spurned lovers and Muslim separatists in recent years.
Of course, a fatal explosion is a fatal explosion. But let's not be too quick to label it a terrorist attack until more is learned.