Two person died and more than 480 were injured, 41 seriously, when a strong aftershock measuring 6.4 on the Richter scale jolted Qingchuan County in southwest China's Sichuan Province on Sunday afternoon.

The strongest aftershock since the 8.0-magnitude Wenchuan County quake on May 12 also destroyed or severely damaged about 270,000 houses, and like the original quake, was felt across China.

In Qingchuan County, the epicenter of the aftershock, 359 people had been injured as of 7 p.m. Sunday while nine villages and towns lost telephone services, according to the disaster relief headquarters in the county.

Longnan City in northwest China's Gansu Province reported one death and 109 injuries with 15 in serious condition. The victim was killed by the rolling stones from a mountain.

The other death was reported in Guangyuan City, Sichuan province.

About 71,300 houses collapsed and more than 200,000 others were in danger of collapse after the aftershock in Guangyuan, said Wang Fei, an official with the disaster relief office in the city. He said details about the victims were not immediately available.

Wang said a mud-rock flow triggered by the aftershock had disrupted traffic from Qingchuan County to Guangyuan City, but no serious landslides were immediately reported.

In Ningqiang County in northwest China's Shaanxi Province, at least 20 people were injured, two seriously. The county, which borders Qingchuan, also reported a large number of collapsed houses in rural areas.

"No death has been reported so far, but many ramshackle houses in the town seat collapsed in the aftershock," said Zhu Lin, an official in Bikou Town, Wenxian County.

Sunday's aftershock hit at 4:21 p.m. and was felt in many parts of Sichuan, including provincial capital Chengdu, said Hou Jianmin, a senior engineer with the China National Seismic Network.

The network located the epicenter of the tremor at 32.6 degrees north latitude and 105.4 degrees east longitude in Qingchuan County, Guangyuan City, which sits on the northeastern border of Sichuan Province and neighbors Gansu and Shaanxi provinces in northwest China.

"We were at a temporary office of the local government and all of a sudden, everything in the room began rocking back and forth," said a CCTV reporter in Qingchuan. "The computer almost slipped from the desk and tiles fell from the roof. Everyone panicked."

A store keeper in Mianyang City, south of Qingchuan, said his store creaked during the aftershock and everyone fled. "We couldn't even stand still," he said.

"I could feel the ground and the mountain shaking," said a CCTV reporter in Beichuan County, which was hardest-hit by the May 12 quake.

Xinhua reporter Hai Mingwei said a plastic water bottle, placed upside down on his floor-standing air conditioner at home in downtown Chengdu, fell in the aftershock. "Although thousands of aftershocks have been felt since May 12, this is the first time the bottle fell," he said.

Since the devastating May 12 quake, many local residents have kept bottles in such positions at home as makeshift quake alerts.

The aftershock was said to have lasted for about a minute and many high-rises in Chengdu rocked slightly.

A Beijinger said he felt the aftershock, too, from his 25th floor office. Those on the lower floors of buildings did not feel the tremor.

The tremor was also felt in Xi'an, capital of the northwestern Shaanxi Province, where citizens fled their homes and offices for the comparative safety of open spaces.

A hotel worker in Shaanxi's Hanzhong City said she felt clearly the aftershock was strong and "next only to the May 12 quake".

About 40 minutes before the aftershock, local residents said the weather in Hanzhong City became overcast and high winds began to blow.

Mobile communication was interrupted, at least temporarily.

In Lueyang County, Hanzhong, the aftershock caused a cave-in on a provincial highway and disrupted traffic, said the county's publicity official, Chen Weiming.

Chen said no casualties had been reported, but some houses collapsed and landslides occurred.

Many feared the aftershock and subsequent landslides might hamper some 1,800 rescuers as they trekked toward a large quake lake at Tangjiashan, where they hoped to blast the lake barrier on Sunday night, before it bursts and causes a flood. Earlier attempts to carry out the mission by helicopter were hampered by bad weather.

The Tangjiashan quake lake, which is in danger of bursting as water builds up in it, is one of the more than 30 such lakes in rivers blocked by landslides from the earthquake and thousands of aftershocks.

The lake is 3.2 km upstream from the Beichuan County seat, from which thousands of survivors have been evacuated since Wednesday.

Its barrier is in danger of bursting as the water level rose by nearly 2 meters on Saturday to 723 meters, only 29 meters below the lowest part of the barrier, which measured 752 meters high.

Nearly 8,000 aftershocks have been reported in Sichuan Province following the May 12 earthquake. The known death toll hit 62,664 on Sunday, including 62,161 in Sichuan alone.

(Xinhua News Agency May 25, 2008)