A major fire forced the closure of Nairobi's main international airport early Wednesday as crews battled the blaze which engulfed an entire terminal building. "The airport has been closed down. Flights routed to Mombasa and Eldoret airports as primary landing. The fire is massive," dpa quoted Kenya's Interior Ministry as saying. Images showed large flames and huge columns of thick black smoke billowing from the international arrivals and departure areas at Jomo Kenyatta International Airport. There were no reported casualties. Those who landed at the airport but had not yet disembarked from their aircraft were evacuated, the ministry said. The cause of the blaze was not immediately known. More emergency crews were being dispatched to the airport, including fire trucks and ambulances, according to the ministry and the Red Cross.