At least one person has been killed and several others injured in a blast in Kenya's capital, Nairobi, police say.
The blast happened during the morning rush hour
Witnesses say the explosion happened outside a cafe near the Ambassador Hotel in the centre of the city.
Police are playing down reports of a suicide bomber whilst carrying out post mortem examinations and forensic tests.
The area has been sealed off by police and the military. The blast was close to the site of the US embassy bombing nine years ago which killed 213 people.
The al-Qaeda network claimed responsibity for the 1998 attack.
The explosion happened at about 0800 local time (0500 GMT) outside the City Gate Restaurant as people were travelling to work.
It ripped through a café sending shards of glass flying and throwing people to the ground.
One eyewitness told the BBC from hospital that he was knocked to the floor by a man running away just before the explosion.
Robert Maritim said he had been having his shoes shined near the blast and believed the man killed was a street sweeper.
Another witness said a man detonated a bomb inside the cafe. Other reports said it was a grenade blast outside.
Shop windows nearby were shattered and the area has now been cordoned off as anti-terrorist police with sniffer dogs comb the scene for further explosives.
Police later said one person had been killed and 30 people hurt in the blast.
Torn pieces of the Koran were found near a body outside the cafe but at this stage it is not clear if they are linked to this attack, the BBC's Karen Allen in Nairobi says.
Last week, more than 30 people were killed in Nairobi during a three-day police crackdown on suspected members of the outlawed Mungiki sect.