A massive fire engulfed the arrivals hall at Kenya's main international airport early on Wednesday, forcing east Africa's largest airport to close and the rerouting of all inbound flights.

Dark black smoke that shot skyward was visible across much of Nairobi as emergency teams battled the blaze. Stranded passengers stood on sidewalks outside the airport with their luggage in hand.

"It was huge, the smoke billowing, and it didn't seem to be stopping," said Barry Fisher, who had hoped to fly to Ethiopia today.

Eyewitnesses at the scene said the fire had gutted the international arrivals hall, where passengers pass through immigration and retrieve their luggage. The Kenya Airports Authority said the Jomo Kenyatta International Airport has been closed until further notice so that emergency teams could battle the fire.

While there were no immediate signs that terrorism played any role in the fire, Kenya's anti-terror police boss, Boniface Mwaniki, said that he wanted to wait for the fire to be put out so that he could inspect the scene before making any judgment.

Michael Kamau, the cabinet secretary for transport and infrastructure, said the fire began at 5 a.m. in the immigration section of the arrivals hall. He said no injuries had been reported. Inbound flights were diverted to the coastal city of Mombasa, he said.

As in many countries in East Africa, public sector services like police and fire units are hobbled by small budgets and outdated or no equipment. A British passenger, Martyn Collbeck, said he was surprised that the airport wasn't shut down sooner so that emergency vehicles could respond.

"When I arrived there were one or two fire engines parked outside the international arrivals. It spread very fast," said Collbeck, who had been scheduled to fly back to London on an early morning KLM flight. "There were a couple of explosions which I think were a couple of gas canisters." But, he added: "I would have expected more fire engines to respond faster."

The Nairobi airport is the busiest airport in East Africa, and its closure is likely to affect flights throughout the region.