Two persons were killed and another was injured as an old building collapsed in central part of the city following heavy rains early on Monday, police said.The two-storey residential building near Sealdah's Baithakkhana Bazar area, that was declared as a "dangerous building" by the Kolkata Municipal Corporation (KMC) a couple of years ago, collapsed at around 2.30 a.m. on Monday."Manik Jana, 48, a resident of West Midnapore district and Gopal Chandra Naskar, 62, of South 24 Parganas district were killed in the building collapse."The two were passing by the road beside the building when the accident happened," an officer from the Muchipara police station said."It seems continuous rain over the last two days might have caused the fragile building to collapse. Another person was injured in the incident as well," he said.Apart from police, a team of state disaster management and fire brigade personnel rushed to the spot to conduct the rescue operation."There were a few people living in the ground floor of the building but they escaped unharmed," the officer added.