A large fire engulfed Nairobi's Jomo Kenyatta International airport's arrival hall, forcing the cancellation of dozens of flights.
By late Wednesday, the airport, East Africa's largest transport hub, re-opened for domestic and cargo flights, officials said.
Kenya Airways said its first overseas flights from London and Bangkok would arrive, as scheduled, early on Thursday and will be processed through the domestic terminal.
The fire started at around 5:00am local time (02:00 GMT) in the immigration section of the departure lounge and spread to the international arrivals area.
There were no reports of casualties, but Mutea Iringo, a senior official at Kenya's interior and national coordination ministry, said the fire was "massive", adding that the arrivals and immigration sections were "totally damaged".
Boniface Mwaniki, Kenya's anti-terror police chief, said he was waiting for more information before completely ruling out terrorism.
Kenya's President Uhuru Kenyatta said the cause of the fire was being investigated and that "there is no reason to speculate at this point".
By 08:00 GMT, firefighters said they had managed to bring the blaze under control, reported Al Jazeera's Catherine Soi from the scene of the fire. All roads around the airport had been closed except to emergency traffic after the fire broke out.
Stranded passengers stood on sidewalks outside the airport with their luggage in hand.
Al Jazeera's Soi reported that the government had set up a crisis team and investigators were looking into the cause of the blaze.
"From the face of it, the damage looks colossal, but that is something we will be told [...] once the assessment is done," she said.
She added that the authorities will monitor flights on Wednesday and Thursday and that some of the flights will be diverted to other airports in the region.
"However," she said, "those airports are small with a limited capacity".
Earlier, images on Kenyan media showed flames rising high in the sky and billowing clouds of black smoke out of the main arrivals and departures terminal, with dozens of police and fire trucks at the scene.
The airport serves as a regional hub for east Africa, with many long-distance international flights landing there to connect to countries across the region.
Wednesday's fire comes less than 48 hours after a fuel jet pump failure caused huge delays at the airport, forcing some flights to be rerouted to the airport in the coastal town of Mombasa, Entebbe International Airport in Uganda and Kigali International Airport in Rwanda.