Video captures deadly pipeline explosion

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ZHONGWEI, China  (CNN) - A pipeline explosion on Thursday killed three and injured four others in Zhongwei County of northwest China's Ningxia Hui Autonomous Region.  
The explosion occurred at 3:01 p.m. Thursday in front of Shaoqiaotou Hotel located on Wenchang North Street, said local authority.

The explosion killed three and injured four others as of 15:00 p.m. Friday.
Authority suspects that electrical workers operating in front of the hotel drilled through accidentally the pipeline, causing gas leakage and the subsequent explosion, but they will continue investigating the explosion.

The surveillance video shows two blasts. Flames reached as high as three meter, setting a nearby car and stores on fire. The blast waves shattered windows of 20 stores and residential buildings within 50 meters.

The blasts caused cave-ins in Shaoqiaotou Hotel, according to the authority.
"I jumped out of the chair when hearing the blast. I saw flames and thick smokes out of my window. I saw three people wrapped in quilts jumping down the building from the window to the north," said Wang Bing, a witness.

Local fire department rushed 50 firefighters and 8 fire trucks to the site.  
The fire was put out in over an hour.  

The injured have been sent to local hospital, said local authority.