Captain Rhyl Jones, garrison engineer of the British Army in Kenya, said: "It was probably commercial explosives, because of the effect that it had on the buildings in the area."
The bomb exploded in a car park between the US embassy building and the Co-Operative House. Ufundi House, a five-storey building in front of the car park and sandwiched between the embassy building and Co-Operative House, was levelled.
"Most of the explosion went upwards. Obviously the base of the vehicle it was in acted as a shield for the charge and that was why the damage was at a high level," Capt Jones said.
He was told by the British High Commission to send as many troops as he could into Nairobi city centre to assist the US embassy.
He arrived at the scene shortly after midday - just over an hour after the explosion.
"Most of the troops with me have served in Northern Ireland and the Falklands and are used to these sort of situations. It is certainly the biggest bomb I have ever seen," Capt Jones said, adding that any number of commercial explosives could have been used, including ammonium phosphate and plastic explosives. "I reckon it was a pretty well-made bomb. I don't think it was manufactured locally. I am only surmising, but I would imagine it was manufactured somewhere else and shipped in."Reuse content