HAIKOU, (Xinhua) -- Tropical Storm Prapiroon, packing winds of 90 kilometers per hour, is moving across the South China Sea towards south China's Hainan island, where it is forecast to hit on Wednesday.

A tropical depression grew into Tropical Storm Prapiroon, the region's sixth major storm of the year, at 2 p.m. on Tuesday and became a stronger tropical storm at 8:00 p.m., the Hainan meteorology bureau said.

It has already lashed the northern Philippines, killing five people.

The storm was moving at 15 kilometers per hour and would affect Hainan from Thursday to Saturday, bringing heavy rains and strong winds to the province, warned the bureau.

Prapiroon is the Thai word for rain god.