20120529
AP
NAIROBI, Kenya (AP) — An apparent explosion ripped through a building full of small shops in downtown Nairobi on Monday, wounding an unknown number of people.

The force of the blast ripped apart the one-story building's aluminum roof, but a high-rise building with a glass exterior right next to the blast did not appear to sustain major damage.

There was no immediate word on casualties or what caused the blast.

People with bloody wounds received medical care right after the blast, as authorities tried to usher hundreds of people in the street away from the scene. TV images showed thick black smoke billowing out of the building in the moments after the blast. The smoke then turned white.

Al-Shabab militants from neighboring Somalia have long threatened to carry out substantial attacks in Kenya following Kenya's decision last October to send troops into Somalia to pursue al-Shabab militants.

Kenya has suffered a series of grenade attacks in recent months, but Monday's blast appeared to have been caused by something larger than a grenade.

The building that was attacked housed a series of small stalls. Items for sale in the shops — like shoes and clothes — were scattered on the ground after the blast.