Rival student groups have clashed over planned constitutional reforms in Kenya bringing Nairobi city centre to a halt with three days of fighting with stones, clubs and whips.
Political analysts fear that the violence may be a harbinger of wider instability in the coming months as the constitutional debate intensifies.
Kenyans see constitutional change as the key to loosening president Daniel arap Moi's grip on their country's political system and to turning around their ailing economy.
It was the first time that students at the University of Nairobi had turned on each other over a political issue. Previous disturbances had centred on issues as diverse as fees, canteen food and power black-outs.
Students are split, with some supporting opposition MP James Orengo while others back government MP Raila Odinga.
The pro-Orengo group advocates a "people-led" process, while the pro-Odinga group favours parliament-driven reform.
Evan Mwangi, a university lecturer and journalist, said: "Students are one of the few groups that can come together in a united front. That is why it suits the government's purposes to keep them divided."
Motorists were stoned, businesses were closed and passers-by injured in the riots. Police intervention was uncharacteristically timid, leading to charges of collusion from anti-government protesters. The ideological conflict had been largely peaceful until January 13, when pro-Orengo students were attacked by a mob of pro-Odinga youths.
Police stationed at nearby parliament buildings failed to intervene, and local press reports suggested the aggressors were aided by plainclothes officers.
The clashes continued through the next day and climaxed when supporters of Mr Odinga, wielding sticks, stones and whips, broke up a campus debate.
The battle spilled over into the city centre, where shoppers fled the streets and businesses closed early. Both students and journalists were injured in the fracas.
Joseph Kioko, of the Students' Organisation of Nairobi University, led the pro-Orengo students. The students who support Mr Odinga do not have any formalised grouping.
There is a tribal dimension to the violence. SONU is perceived to be dominated by members of the Kikuyu tribe, while pro-government students are aligned to Mr Odinga's Luo tribe. Some may have been motivated by money. "Some groups support whoever pays the most," Mr Mwangi said.