As many as 35 fire tenders were pressed into service. 35 fire tenders were pressed into service, it took firefighters more than four hours to douse the blaze. It functions under the Ministry of Environment and Forests.Six fire officials were rushed to hospital after they inhaled excessive smoke during the operation.co/ygh6K86G4Y— ANI (@ANI_news) April 26, 2016There were not too many people in the building, which was evacuated by the time fire officials reached at the scene.The fire broke out around 1. It took firefighters more than four hours to douse the blaze after which a cooling operation was launched which lasted for another few hours, a fire official said.Top officials of the police range and Delhi Fire Services rushed to the spot to take stock of the situation.The cause of the fire is yet to be ascertained, a senior police official said.Massive fire engulfs National Museum of Natural History in FICCI building in New Delhi. Their condition is said to be stable now, the official said.Established in 1972, the National Museum of Natural History in New Delhi is one of two museums focusing on nature in India. It quickly spread Double jacket hose to all other floors of the building.45 am on the top floor of the museum, located in FICCI Building in Mandi House, where some repair work was underway.WATCH: Fire which broke out at Delhi's Natural History Museum at around 2 am today morning (earlier visuals)https://t.A massive fire broke out at the National Museum of Natural History in FICCI building in central Delhi in the wee hours of Tuesday. The damage caused by the fire is being estimated.