New Delhi: Parts of an under-construction building crumbled in northeast Delhi’s Harsh Vihar Sunday evening, with at least two people feared trapped under the rubble.It was originally an old, single-storey structure on which another floor was being built. At 6.45 pm, a slab on the first floor appeared to have collapsed, bringing parts of the building down.Locals started removing the debris and searching for those feared trapped. Five fire tenders were rushed to the spot, along with National Disaster Response Force (NDRF) teams, civil defence, NDMA, paramilitary and Delhi Police personnel, for rescue operations. Four ambulances were also scrambled.The rescue effort was complicated by narrow entry and exit points. “The area is completely enclosed, which intitially made it difficult to even identify the exact building that collapsed,” additional DCP Sandeep Lamba said.A local said that the slab on the roof of the first floor of the building was weak and a new slab was being constructed to replace it. “Suddenly, the old one gave in, causing the new slab to also collapse,” he said. Dilip, who along with 16 labourers was working at the building, also toed this line, saying, “The new roof slab had just been built before the incident.”Police and locals said that two people might have been trapped under the collapsed structure, with rescue operations involving sniffer dogs stretching into the night.A video of the incident shows rescue personnel shouting “koi hai?” and using mobile torches to illuminate the area in a desperate search for those feared trapped. A pile of bricks can be seen on the sides, while rebars, which support roof slabs, are seen bent and stripped of concrete.Earlier this month, at least four people died when a residential building collapsed in Seemapuri. In Sept, seven people were killed when a five-storey building collapsed in Satya Niketan. The building came crashing down like a pack of cards after a retaining wall on the ground floor was removed to merge two shops.