LAHORE: An explosion occurring in a house in Johar Town has caused at least 23 people to sustain injuries and claimed the lives of three people. Witnesses are stating that the explosion had caused the windows of the houses and buildings to shatter. The injured people have been taken to Jinnah Hospital via autos and private cars, the rescue officials said. The Jinnah Hospital management has asked people to come forward and donate blood for the injured, adding that treatment is being provided to the wounded. Three of the injured are in critical condition. According to sources, the blast was caused by a main gas pipeline exploding in the residential area. However, it is yet not clear what exactly caused the blast. They said that the explosion was so powerful that the windowpanes of adjoining buildings were shattered. A rickshaw and motorcycle parked nearby were completely destroyed by the blast, the police said. Capital City Police Officer (CCPO) Ghulam Mahmood Dogar visited the site of the blast. He said the cause of the explosion has not yet been determined. Meanwhile, Punjab Chief Minister Usman Buzdar took notice of the blast and directed the provincial police chief to submit a report after conducting a thorough investigation into it. He instructed that those responsible for the explosion be brought to justice at once and the best possible medical aid be provided to the injured. He called for declaring a medical emergency at the Jinnah Hospital and other health facilities in the provincial capital.