CHENGDU - More than 100 people were killed and thousands injured after a strong quake struck southwest China's Sichuan Province Saturday morning, triggering massive rescue efforts.

The 7.0-magnitude earthquake hit Lushan county of Ya'an City in the province at 8:02 am Saturday Beijing Time. At least?156 people were killed, according to the China Earthquake Administration on Saturday afternoon.

More than 5,500 people were injured, according to a statement from the Lushan county publicity department at Saturday noon, adding that about 140,000 people will have to be relocated.

The epicenter of the quake, with a depth of 13 km, was monitored at 30.3 degrees north latitude and 103.0 degrees east longitude. It is one of the most destructive earthqukes in China in recent years. A 8.0-magnitude quake in Wenchuan county in Sichuan Province left 87,000 dead or missing in May 12, 2008.

Ya'an has a population of 1.53 million and is known as the hometown of the giant panda. It is about 140 kilometers away from the provincial capital Chengdu and about 250 km from Wenchuan.

Chinese President Xi Jinping on Saturday ordered troops in the quake-hit zone to make "every possible effort" to rescue.

The troops must be quickly dispatched to the front line of the quake-relief work to rescue residents and treat the injured in every possible way, Xi said.

Premier Li Keqiang arrived at the epicenter Saturday afternoon. He convened emergency meetings during his flight to direct quake-relief work.

"The current most urgent issue is grasping the first 24 hours after the quake's occurrence, the golden time for saving lives, to take scientific rescue measures and save peoples' lives," Li said. RESCUE UNDERWAY

The hardest-hit areas are in the townships of Longmen and Qingren, said Jin Zelin, an official with the provincial armed police corps.

"At least 24 people have died and 300 are injured, of whom 50 seriously, in Longmen town," a township government official told Xinhua.

"Old houses in Gucheng village with a population of 3,000 totally collapsed. More than 95 percent of the houses in the village are not fit for living in," he said.

Vehicles damaged by rolling rocks were seen in Lushan. Houses along a street in the Lushan county seat have also collapsed. Helicopters are hovering, according to Xinhua reporters at the scene.

Patients are receiving medical treatment on the ground in front of the Lushan County Hospital.

More than 500 people are injured, 135 seriously, said Le Zhiyong, deputy head of the hospital.

Three townships of Taiping, Baosheng and Dachuan in Lushan county are out of the contact. The water and electricity supply in the county has been cut off due to the quake. Most of the buildings in the old urban area of Lushan county and Longmen township collapsed in the quake, according to the local government's statement.

Landslides have blocked traffic in many places across the county and two barrier lakes caused by the landslides are posing risks for the rescue efforts, it said.

About 2,000 rescuers organized by the county government are working in nine towns, it said.

Bifeng Gorge base, a panda research base affiliated to the Wolong Giant Panda Protection and Research Center which is only 47 km from the epicenter, has no reports of human or panda casualties, said Yu Xiaoying, a staff member with the Wolong center.

Huang Qiqun was working at the first floor of a bamboo weaving factory in Longmen township when the earthquake destroyed the building.

Huang, in his 40s, was dug out of the debris by his colleagues and sent to hospital by motorbike, his daughter told Xinhua. Huang is suffering from a head injury.

Multiple temporary settlements with food and water supplies have been established in the county seat, Xinhua reporters said.

A 5.3-magnitude earthquake jolted the border areas between the counties of Lushan and Tianquan at about 11:34 a.m., the strongest aftershock after the 7.0-magnitude quake, according to the provincial seismological bureau.

About 3,870 armed police have arrived in Lushan county to assist with rescue efforts. INFRASTRUCTURE DISRUPTED

About 200 technicians from China Mobile Limited's Sichuan branch have been dispatched to disaster-hit areas to repair the telecommunications network.

Infrastructures remain intact in Sichuan but are badly damaged and broken in the epicenter and nearby.

The State Grid Corporation of China said the major lines in the province are operating smoothly, but those in the quake-hit area are severely damaged.

In Lushan county, two transformer substations have halted service, with one of them unable to resume operation. Five hydropower stations in Ya'an are disconnected.

According to the nation's major telecommunications companies, mobile phone services are suspended in the epicenter, with interruptions in the province.

As many as 279 telecommunication base stations have collapsed due to the quake.

Sichuan has rich oil and gas resources, with many pipelines and refineries. Sinopec, Asia's largest refiner, said no damage had been reported at its production facilities in the quake-hit regions. NOT AN AFTERSHOCK OF WENCHUAN QUAKE

The Ya'an quake has resulted in serious casualties and economic losses, but it is not expected to be as disastrous as the 8.0-magnitude Wenchuan quake, said Pan Huaiwen, director of the China Earthquake Networks Center (CENC).

Possibilities of aftershocks stronger than 7.0-magnitude are small, he said.

But Pan warned of aftershocks and secondary disasters, including landslides, mud-rock flows, and the collapse of caves and riverbanks.

A total of 264 aftershocks had been monitored as of 12 p.m., two of which were above 5.0-magnitude, according to the CENC.

Jiang Haikun, an official with the CENC's forecasting department, said the Ya'an quake resembles that of the Wenchuan disaster, as both earthquakes were formed in a similar way, occurring on the Longmen mountain fault zone.

Earthquakes on this 500-km belt are not frequent, but very powerful. Twelve quakes above 5.0-magnitude have occurred since 1900, including Wenchuan as the most powerful one, Jiang said.

The Ya'an quake was not an aftershock of the Wenchuan earthquake, he said.

A total of 12 earthquakes at 5.0-magnitude or above have occurred in the area within 100 kilometers of its epicenter since 1900, including the devastating Wenchuan quake in 2008.

Live report: 7.0-magnitude quake hits Sichuan