Rare storms with typhoon-like winds have killed at least seven people in China's southern Jiangxi province since the weekend, three of them blown out of their high-rise apartments in their sleep.

The extreme weather, which began on March 31, has engulfed nine cities including Nanchang and Jiujiang with 93,000 people in 54 counties affected, said the Jiangxi provincial emergency flood control headquarters.

On Sunday, freak storms led to gusts that ripped door-size windows off frames in two apartments in a high-rise building in Nanchang, the provincial capital. Three people were pulled from their beds through the holes, plunging to their deaths, according to local media reports.

Officials on Wednesday said seven people so far have died across the province and 552 had to be emergency evacuated. They also said 2,751 houses were damaged.

Accompanied by dramatic sheet lightning, pounding rain and hailstones the size of golf balls, the powerful storms - the most severe in more than a decade - also caused 150 million yuan ($21 million) in economic losses, local officials said.

China's weather bureau had issued warnings of violent winds with speeds of up to level 12 on local wind scales, equal to a Category I hurricane.

Winds of such intensity are common when typhoons, as hurricanes are called in China and elsewhere in East Asia, make landfall but are rarely found inland such as landlocked Jiangxi.

China's national weather forecaster kept its highest severe convective weather warning advisory - orange - in several areas of southeastern China as strong winds, hail and thunderstorms continue through Wednesday.

The forecaster on Tuesday issued the first orange alert for severe convective weather since 2013, state media reported.

China has a three-tier, color-coded weather warning system for severe convective weather, with orange representing the most severe warning, followed by yellow and blue.

($1 = 7.2348 Chinese yuan renminbi) (Reporting by Qiaoyi Li and Bernard Orr; Editing by Philippa Fletcher)