The quake also destroyed an important ancient city in the Langzhong City, felling a 32-meter-tall tower about 400 years old.

"I felt the earth shaking, and a long crack appeared in the tower, and in less than two minutes, the tower fell to the ground,” said Li Huiqiong, an employee with the scenic area of the city.

A house in Dujiangyan city of southwest China's Sichuan province collapsed from a major quake measuring 7.8 on the Richter Scale in Wenchuan on Monday, May 12. A large number of houses have also collapsed in its neighboring Dujiangyan city.

The quake, measuring 7.8 on the Richter scale, hit Sichuan at 2:28 PM on Monday. It was the worst earthquake to strike China since the Tangshan earthquake in 1976, which claimed 242,000 lives.

A spokesman with China Seismological Bureau said the intense quake was felt in at least 16 provinces, municipalities and autonomous regions, including Beijing, Shanghai and Tibet.

The shocks leveled buildings, cut transport and electricity supplies, and caused flights to and from the affected areas to be canceled or postponed.

The tremors were even felt in the Thai capital of Bangkok, 1,800 kilometers from the epicenter.

In regions neighboring Sichuan, 85 were killed in Shaanxi Province, at least 157 in Gansu Province, 50 in Chongqing Municipality, one in Yunnan Province and one in Henan Province, according to local authorities.

China has launched emergency rescue operations in the quake-hit zones. Premier Wen Jiabao, who arrived near the quake center Monday afternoon by plane, said the quake was a "major disaster" and called for calm, confidence and courage. He urged the rescuers to seize every minute to enter the worst-hit areas.

By 6:30 AM Tuesday, more than 16,760 troops and armed police have been dispatched into the quake-hit areas. More than 34,000 others are on their way by air, rails, motor vehicles and on food.

Early Tuesday, dozens of military vehicles are heading to Beichuan County, where officials said up to 5,000 people were said dead.

Escaped villagers said the old town of Beichuan was tightly covered by giant swaths of debris slides, and the new town also suffered grave damages, particularly kindergartens, primary and middle schools, and vocational schools.

The Mianyang city disaster relief headquarters said about 80 percent of the buildings in the old town area in Beichuan collapsed, and more than 60 percent of the buildings in the new town were wracked.

Cofferdams formed by the landslides at the upper stream of rivers in the county threaten to inundate the downstream areas in Beichuan.

As rescuers moved toward the quake-hit centers, rocks slid down the mountains and piled upon boulders the size of a house which already jammed up the road sections.

According to a statement posted on the website of the Tibetan-Qiang Autonomous Prefecture of Aba, which administers Wenchuan, officials are getting information on casualties and damages in the county, but there is still no news about the situation in the townships of Yingxiu, Wolong and Xuankou, which are located exactly at the epicenter.

At least 157 killed in two cities of Gansu

At least 157 people have been killed in two cities near the epicenter of a strong earthquake that struck southwest China Monday, local authorities said on Tuesday.

Some 150 people were left dead and 738 others injured in the Longnan City, northwest China's Gansu Province, said a spokesman with the city government.

The 7.8-magnitude earthquake rocked Wenchuan County in southwest China's Sichuan Province at 2:28 p.m. Monday. More than 1,000 aftershocks have been recorded.

The quake was strongly felt in Longnan, about 240 km northeast of Wenchuan.

Xinhua reporters saw hundreds of people, including citizens and farmers, spent Monday night in the open air, daring not go home.