Kanpur, Sept. 29 -- Four people were killed and three others were injured after a gas cylinder exploded in Malwan in Fatehpur on Monday evening, bringing down three adjoining houses and trapping several people under the debris. Seven people were taken out of the rubble, while the possibility of more people being trapped remains, the police said. The blast took place at the house of Suresh Gupta in Malwan while food was being prepared. The explosion was so powerful that the roofs of three houses, including Gupta's, collapsed. Police and fire service teams reached the spot after being alerted, and rescue operations began with the help of local residents. Four of those rescued were later declared dead, while three others were taken to the medical college for treatment. One of the injured is reported to be in critical condition. Senior police and administrative officers are at the spot and supervising the rescue operation. Teams are continuing to search through the debris amid fears that more people may still be trapped inside the collapsed houses....