JOHANNESBURG, South Africa -- When four large explosions reverberated through Nairobi's Westgate shopping mall during a terrorist siege Monday, sending a pall of black smoke into the air, the official Kenyan response -- that the militants had set fire to mattresses -- strained credulity.
Later, the same official, Interior Minister Joseph Ole Lenku, blamed the gunmen for the collapse of a section of the mall, which is believed to have buried some hostages and possibly some militants as well. It's not known whether they were alive or dead when three floors caved in, or how many bodies there might be under the rubble.
But an unidentified Kenyan official, in comments to the Associated Press, admitted for the first time Friday that it was the actions of the Kenyan military that caused the collapse.
The official also told the AP that Kenyan troops fired rocket-propelled grenades inside the mall, but did not explain what caused the four explosions. Many observers believe it is likely that the building collapse occurred after the explosions.
Lenku initially said that the mattress fire structurally weakened the mall, causing its collapse. He retreated from that statement Wednesday, saying engineers were examining the causes, but insisted that the number of hostages' bodies buried in the rubble was "insignificant."
Kenyan authorities have confirmed 72 deaths in the clash, including five militants and six soldiers. According to the Kenya Red Cross Society, 61 people are still missing.
The forensic investigation and excavation of the mall, to find any more bodies and to try to establish the identities of the attackers, is expected to take more than a week.
Forensic investigators from the United States, Israel, Germany, Britain and Canada are involved in the investigation.