A crowd gathers at the scene following an explosion in Nairobi, Kenya. The cause of the blast was not clear; the capital city was attacked years ago by al-Qaida terrorists but more recently has seen trouble with gangsters linked to an outlawed sect called the Mungiki.

Nairobi, Kenya ? An explosion Monday in the Kenyan capital’s packed business district killed two people and injured more than 30, leaving behind a corpse with half his body blown away and sending hundreds of rush hour commuters ducking for cover from flying shrapnel.

The cause of the blast outside the Ambassadeur Hotel was not immediately clear, but Police Commissioner Mohamed Hussein Ali said it was “something that somebody was carrying.” In response to questions about whether the explosion was a suicide attack, he said: “That type of speculation is not factual at all.”

Police spokesman Eric Kiraithe said initial investigations indicate that “the source of the explosion was extremely small,” adding that there were no traces of “high explosives” at the scene.

The last major bombing here was in 1998, when the U.S. embassies in Nairobi and Dar es Salaam, Tanzania, were simultaneously hit, killing 225 people in an attack blamed on al-Qaida. Kenya, one of Africa’s main tourist draws, is relatively peaceful. But it shares a border with Somalia, which is struggling against an Islamic insurgency.

The blast comes at a particularly tumultuous time in the Kenyan capital. Gangsters linked to an outlawed sect called the Mungiki have been blamed for a string of beheadings in recent months. More than 30 people were killed by police last week in raids on a Nairobi slum believed to be a stronghold for the gang.

Leaflets allegedly circulated by the group call on Kenyan youths to join up and prepare for an uprising against the government.

Witnesses said a man left a bag at a shoe shiner’s stand and sprinted down the street seconds before Monday’s blast.

Robert Maritim, who had just finished having his shoes shined, said the man pushed him as he took off down Moi Avenue, one of Nairobi’s main thoroughfares. As Maritim got up, the blast lifted him off the ground and smashed him into a tree, injuring his back.

“I am thanking God,” Maritim, 24, told The Associated Press from Nairobi’s Kenyatta Hospital.

One of the men working at the shoe shine stand was injured, he said.

Edward Tongai, a shoe shiner, echoed Maritim’s account, adding that the man had tried to get onto a city bus before having his shoes shined. But the conductor told him the bus was full, Tongai said.