RAIPUR,Jan15: A BSF helicopter crashed during a test flight at the Mana airport in Raipur on Sunday injuring five persons, including the pilots, officials said.The advance light helicopter came crashing on the runway from a height of 100 feet during the test flight, injuring pilot P D Tiwari, co-pilot Brig P D Tiwari, and technical officers Anand Bharti, Pankaj Pal and Subroto Chandra, SP Diptanshu Kabra said. The injured have been taken to hospital where the condition of Tiwari is state to be critical.According to Kabra, the helicopter was damaged due to the crash. Work is on to remove it from the runway.A team of senior police officials of the state have rushed to the site and the cause behind the mishap is being ascertained, he said.Mana Airport general manager Anil Rai said after reaching a height of about 100 feet the helicopter, which was carrying five persons, crashed on the runway.Not much is known about the crash as the two pilots are injured, he said.Due to the crash, a Mumbai-bound Air India flight and a Jet Airways flight to Bangalore were delayed. Other flight operations too were affected, he said.The incident would be probed by the Directorate General of Civil Aviation (DGCA), Rai said.The BSF is deployed in the Naxal-hit Kanker district in Chhattisgarh and uses the helicopters to transport injured jawans and relief material.