QINGDAO - At least 35 people were killed and 166 others injured after a leaking pipeline caught fire and exploded on Friday morning in the coastal city of Qingdao in East China's Shandong province, local authorities said.

Among the 166 injured, 65 are in serious conditions, according to a statement posted on Friday night on the official microblog of the Qingdao municipal health bureau on Sina Weibo, China's Twitter-like microblogging service.

The accident happened around 10:30 a.m. at the crossing between Haihe Road and Zhaitangdao Road in Huangdao District as workers were repairing a petroleum pipeline, according to the Qingdao government's publicity office. The pipeline had begun leaking oil at around 3 a.m. at the crossing between Qinghuangdao Road and Zhaitangdao Road, the office said.

A dog stands in front of an overturned vehicle near the site of an explostion in Huangdao District in Qingdao, East China's Shandong province, Nov 22. The blast happened after a leaking pipeliine caught fire. [icpress.cn]

Oil leaked from the Sinopec pipeline into the municipal pipe network, which caused the explosion, according to an initial investigation by the rescue headquarters at the scene.

The district government has ruled out a terror attack as the cause, while the State Administration of Work Safety has sent a work team to the scene to guide the rescue efforts.

Chinese President Xi Jinping on Friday asked for maximum effort in the search for survivors of the blast. He also asked local authorities to spare no effort to rescue the injured, find the cause of the accident and strengthen safety.

Premier Li Keqiang also urged local authorities to improve inspection and supervision and make sure safety procedures are followed.

With the authority of Xi and Li, a team led by State Councilor Wang Yong has been dispatched to direct rescue work.

The Qingdao municipal government has ordered scrutiny of the safety of its pipeline network after the accident.

About 1,000 square meters of road surface was covered in leaked oil at Zhaitangdao Road. Some of the oil had spilled into Jiaozhou Bay through the rainwater pipeline, and about 3,000 square meters of sea water was polluted by oil, said the rescue headquarters.

Fires and explosions also occurred on the polluted sea waters at the entrance to the bay, according to the headquarters.

An oil belt with a width of two to three meters could be seen in waters around the site of the explosion as of 2:40 p.m. No new oil leakage from the pipeline had been found, according to a Xinhua reporter at the scene.

Oil flow through the pipeline was shut off at about 3:15 a.m. The fire has been put out, and barricades have been set up to stop the oil from entering the sea, according to a comment posted on Friday afternoon on the official microblog of the Qingdao municipal environmental protection bureau on Sina Weibo.

Environmental monitoring showed that the concentration of toxic materials in the air was below the national standard. The local government has told citizens to remain calm.

Peng Yu, a Qingdao resident, hoped that the government would continue to release the air quality reports to protect residents' health.

Xinhua reporters saw cracks in the streets, the longest of which was about 1.5 km.

"I have only seen this in disaster films," said a rescuer surnamed Xue, who drove past the streets where the blast happened.

Xue told Xinhua he was astonished by the sight of a bus sandwiched between huge cracks in the street with passengers trapped inside.

"Some cars along the street are turned over, some are covered with concrete slabs, and some others have lost their window glass, " he said.

Wang Aihua, a doctor at Huangdao District People's Hospital, said they have received more than 20 patients injured in the accident and are expecting more.

Some residents have evacuated from the area for fear that a second explosion might occur, added Wang.

A staff member from Huangdao District Hospital of Traditional Chinese Medicine told a Xinhua reporter by phone on Friday night that the hospital had received more than 50 patients since the blast, with some of them under emergency treatment.

The male staff member, speaking on condition of anonymity, confirmed that there had been fatalities, but he refused to reveal a number.

Most of the injuries were fractures due to the force of the blast, he said.

More then 800 doctors and nurses from the hospital have participated in the rescue efforts, he added.

The 176-km pipeline is owned by Sinopec, China's largest oil refiner, and links oil depots in Huangdao with Weifang City, home to a few petrochemical plants.

The pipeline, with a total investment of 1.3 billion yuan (211.8 million U.S. dollars), was put into operation this August. It has an annual transportation capacity of 15 million tonnes.

Huangdao District is connected with the city proper by the Qingdao Jiaozhou Bay Bridge.

Xinhua reporters said the exit on the bridge leading to Huangdao has been temporarily closed and only emergency vehicles are allowed to enter. Local traffic authorities have urged drivers to make way for rescue vehicles.