“The body is badly damaged, and we are only able to collect pieces that are strewn all over,” regional police chief Charlton Mureithi told reporters at the scene on Sunday morning.
“We believe this man was trying to assemble it (the bomb) when it went off on him,” he said, adding that two pistols, including one stolen from the police, had been found at the scene.
A police source told Capital FM News that they are investigating to establish if the suicide bomber was targeting a Narc Kenya political rally which is scheduled to be held at the grounds this afternoon.
The bomb blast is the latest in a string of attacks in Garissa — which lies some 120 kilometres (75 miles) from Somalia, where Kenyan troops are fighting Islamist insurgents — as well as elsewhere in Kenya.
Attacks have increased in Kenya since Nairobi sent soldiers into Somalia to fight Al-Qaeda-linked Al Shabaab insurgents in October 2011, prompting warnings of revenge from the extremists.
The violence has been blamed on the insurgents or their Kenyan supporters, although no attacks have been claimed by the Al Shabaab.
The militant group is on the back foot in southern Somalia after losing a series of key towns to African Union troops — including the Kenyan army — as well as allied Somali forces and Ethiopian soldiers.
However, the insurgents continue to stage guerrilla attacks, raising security concerns in Kenya ahead of the March 4 election.