Kenyan police have fired tear gas at rioters attacking ethnic Somalis in the Nairobi district of "Little Mogadishu".
The flare up in violence, which saw people hurling stones and smashing windows, came after a weekend bomb attack that killed nine people in the area.
The violence on Monday coincided with the beginning of voter registration for the general election in March this year.
In 2007, the last time that such a national poll was held, a dispute over the results fuelled ethnic violence that killed more than 1,200 people and forced about 300,000 from their homes.
Angry mobs broke into Somali homes and shops in anger at Sunday's attack on a minibus which killed at least nine people in Nairobi's Eastleigh district which is dominated by Somali Kenyans and their ethnic kin who have fled fighting in Somalia.
Ethnic Somalis, some armed with machetes, fought back and hurled stones at their attackers who responded with sling shots and stones. Paramilitary police fired volleys of teargas to prise the battling factions apart.
"We are trying to create a buffer zone so that people cannot cross over," Moses Ombati, the Nairobi regional police commander, told reporters, pointing to a road that he said formed a rough boundary between the two communities.
"These people are neighbours and business partners who need each other, so I don't think it will last long," he said.
Gangs of looters ran amok as the security forces fought to quell the violence. One Somali trader, who gave her name only as Hamdi for fear of reprisal attacks, said she was worried the unrest would spread throughout Eastleigh's rundown estates.
"I condemn anyone who carried out this heinous act," she said, referring to Sunday's bomb attack. "It's affecting many innocent civilians and is causing the Somali community to be targeted."
Warning shots fired
Authorities have blamed Somali fighters and their sympathisers for grenade and gun attacks in Kenya since Nairobi sent soldiers into neighbouring Somalia last year to drive out al-Shabab rebels, a radical religious group with links to al-Qaeda.
"The xenophobic attacks must be stopped at all costs lest they escalate to unmanageable mayhem at grave costs to the nation"
- Al-Amin Kimathi,
Muslim Human Rights Forum chairman
Attacks have intensified since Kenyan forces, fighting under an African Union banner, and Somali government troops routed al-Shabab from their last major urban bastion, the Somali port of Kismayu last month, forcing the rebels to flee.
Two Kenyan soldiers were shot dead in the eastern town of Garissa, which is a rear base for Kenya troops fighting in Somalia as part of the regional African Union force, on Monday.
In Nairobi's Eastleigh district, also known as "Little Mogadishu", crowds poured through the streets chanting "Somalis must go!", hurling stones and smashing windows of some Somali apartment blocks.
Police fired warning shots in the air, but rioters were undeterred. They demanded that the government improve security in the district, which has borne the brunt of the grenade and gun attacks.
Streets in Eastleigh, a congested residential and business area, were strewn with stones and shattered glass. Shops shuttered windows were and most business were closed in what is one of Nairobi's busiest trading centres.
|The string of attacks on Nairobi over the past year have been blamed on Somali groups [AFP]
People stood on rooftops while some ethnic Somalis gestured for assistance through their windows.
"These Somalis are getting used to this. Every day there is a grenade attack," said Evans, a non-Somali resident of the area wearing sandals and a dirty t-shirt with a print of Che Guevara.
Children in school uniforms and their parents ran from school, after being trapped there by the violence.
Others ran towards the police, with their hands in the air. At least a dozen Kenyan men were laid face down in one truck, as the authorities began to make arrests.
Local businessman Godfrey Biketi who supplies meat to Eastleigh, urged his fellow Kenyans to be calm.
"They should just chill. They're our neighbours," he said of the Somalis. "Even our country is fighting a war in Somalia. Now our country is becoming like theirs, it's not cool," he said.
The Muslim Human Rights Forum said that even if the suspects responsible for Sunday's bombing were proven to be Somalis, it did not mean the whole community was involved.
"The xenophobic attacks must be stopped at all costs lest they escalate to unmanageable mayhem at grave costs to the nation," the group's chairman Al-Amin Kimathi said.