A cargo train has derailed in the crowded Nairobi slum of Kibera, the Kenyan Red Cross said.

The train crashed into makeshift homes on Sunday, trapping scores of people, the organisation said. The Kenyan government's disaster operations office has tweeted that all of the trapped people had been rescued and that five of them had been taken to hospital.

Al Jazeera's Rawya Rageh, however, later tweeted from the scene: "the commanding officer on scene tells me it's not clear if people are trapped underneath the wreckage, we need to lift the wagons to tell."

Transport Minister Michael Kamau, who was also at the scene, told journalists six people had been taken to hospital so far.

"The rescue efforts are under way, we cannot talk of the number of those injured at the moment," Nairobi Police chief Benson Kibue told AFP news agency.

The Kenya Red Cross tweeted that "efforts are under way to remove the wreckage." A police officer said they are trying to bring in a crane, according to Rageh.

"It was a very heavy cargo, that's why it had two engines," said Rageh of the train that was carrying wheat to Uganda, adding that the weight of the load appeared to be the initial cause of the derailment.

No 'missing persons' yet

Kibera is one of Africa's largest slums and is home to an estimated quarter of a million people, according to an NGO that carried out a survey there.

But locals have suggested that casualties might be lower than initially thought due to people having gone to church or returned to their villages for the Christmas holidays.

"The initial report is that people are feared trapped, but so far we have not received reports of any actual missing persons," a Red Cross emergency officer at the scene told AFP.

Rageh said Kamau told reporters that "the government had warned residents not to set homes close to the track."

"But people are saying they don't have a choice to live where they live," Rageh said.

"There's a lot of tension you can feel here. Police are pushing people away, she said, adding that people are concerned their homes will be damaged when the train is flipped over. 

Source: Al Jazeera and agencies