Kenyan police battled with protesters and fired tear gas outside parliament for a second day, as MPs debated a controversial draft constitution.
Protesters want the president's powers reduced
Youths hurled stones at police and one person was shot dead as looters ransacked cars and shops in Nairobi.
President Mwai Kibaki was elected in 2002, partly on a promise to reduce the president's powers within 100 days.
MPs disrupted the debate shouting "Shame, shame", accusing him of being unwilling to give up his powers.
On the second day of protests, college students joined the marchers, who shouted their opposition to the proposed constitutional changes.
Police banned the protests fearing "chaos and mayhem"
The BBC's Wanyama Chebusiri, caught up in the demonstration, said the streets around the parliament were turned into a battlefield between the armed police and demonstrators.
Standing in front of police lines, about 50 people sang songs calling for an uprising.
"Even if you kill us, we still want our constitution," they chanted, according to Reuters news agency.
At least nine people were arrested as police beat demonstrators with truncheons after being pelted with stones.
Police banned the marches, saying troublemakers were planning "chaos and mayhem".
Under the latest draft constitution, a new post of prime minister is being created. However, Mr Kibaki's critics say the president retains most powers.
The issue has deeply divided the Narc coalition which united behind Mr Kibaki in the 2002 election.
The Liberal Democratic Party, led by Raila Odinga, who had been promised the post of prime minister, opposes the changes, as does the opposition Kanu party.
Inside parliament, the atmosphere was tense, as Kanu and LDP MPs interrupted those proposing the motion.
The debate was adjourned until Friday, which is the deadline for parliament to finalise its version of the constitution before Kenyans have their say in a referendum in October.
"Parliament keep off! It is our Constitution," read banners carried by demonstrators, who scuffled with police at various points around parliament on Tuesday.
"There is no jail to accommodate the people of Kenya," one protester told the BBC.
"Judging by the number of policemen, horses and dogs, one would think Kenya is a police state or in a state of emergency," said Kanu Secretary General William Ruto.
Internal Security Minister John Michuki said the government was obliged to control the protesters.
"There was a threat to law and order. We have to keep peace," he told parliament.