A single-storey house collapsed due to an LPG cylinder blast in north Delhi's Mukundpur area on Tuesday, leaving at least four injured, an official of the Delhi Fire Service told PTI.The incident happened at Gali No. 1, Part-2, Ishu Vihar, near the cremation ground. The authority received a call reporting the blast at 9.37 am, saying residents may be trapped under the debris."We got information that a blast took place and a building collapsed due to which some people are trapped. Rescue teams rushed to the spot and launched operations," the officer said, adding that five rescue vehicles were rushed to the spot."Information was received that a blast had taken place and a building had collapsed, trapping people inside. Rescue teams were immediately rushed to the spot and search and rescue operations were launched," a DFS official told the news agency. The official said the blast occurred in a 250-square yard single-storey house.The authorities are clearing debris and searching the collapsed structure to ensure no one remains trapped.The cause of the damage is still being invetsigated.