The outlet of China National Petroleum Corporation (CNPC) located at No. 909, Third Pudong Roadin Puding New District SHANGHAI, Nov. 26 - Improper work practices caused Saturday's blast at a Shanghai gas station that claimed four lives,the municipal government said Sunday.Operations at the gas station, an outlet of China National Petroleum Corporation (CNPC) located at No. 909, Third Pudong Roadin Puding New District, had been suspended since Nov. 11 for a safety inspection.The underground gas tanks needed to be pressurized to carry out the inspection, said an official with the municipal department of publicity. The official, who declined to give his name, said there had been residual gas in the tanks, leading to the explosion at 7:50 a.m. Saturday.Two maintenance workers at the station were killed and two passers-by, a woman and a male cyclist, died after being struck by debris from the blast.The two workers were a male aged 30 from eastern Anhui Province and another male, 46, from neighboring Jiangsu Province.The cyclist, 29, was also from Anhui and the woman, aged 42, was from northwestern Shaanxi Province.The municipal official said compensation for the victims' families was being negotiated.Another 32 people who lived in the area or were passing through were initially hospitalized. Most had been released by Saturday night."Two seriously injured people are still hospitalized, but they are stable," the official said.The two workers were employees of the Shanghai Pacific Gas Co.,Ltd. and the municipal administration of work safety is trying to determine if they received proper training for maintenance work.