At least one person has been injured in a grenade attack in a predominantly Somali district of the Kenyan capital Nairobi, police say.Three grenades were thrown from a vehicle towards shops in Eastleigh, witnesses said.No group has so far said it carried out the attack.However, the area has suffered previous attacks that officials have blamed on Somalia's al-Qaeda-linked al-Shabab militant group.Kenya says al-Shabab is trying to destabilise the country.The Citizen TV station reported that the blast happened on Eastleigh's Muratina road.A reporter for Reuters news agency at the scene said one grenade had hit a butcher's shop next to a guest house, blowing a hole in the wall and shattering windows. The injured person had been a customer at the shop, Reuters said.Eastleigh was hit by two grenade attacks earlier this month that left at least six people dead.In November, Kenya accused al-Shabab of killing seven people in another grenade attack in the area.Last year, Kenya sent its troops to fight al-Shabab in Somalia. They have now joined the 18,000-strong African Union (AU) force supporting the UN-backed government.