Opposition leader Raila Odinga, who claims he was robbed of the presidency in the Dec. 27 election because of vote rigging, called for the nationwide protests despite a government ban on the demonstrations, reported the Associated Press.
Police called for a ban on the three planned days of protests. As a result, shopkeepers boarded windows, traffic came to a standstill in parts of Nairobi, and many Kenyans stayed at home, Reuters reported.
The political crisis has damaged Kenya's democratic credentials, frightened away tourists and is expected to adversely impact an otherwise promising economy.
In downtown Nairobi, riot police on horseback disbursed small groups of protesters, and workers fled from office buildings to avoid the troubles.
In the western towns of Kisumu and Eldoret, thousands of men gathered to march, and police first used tear gas and then gunfire to clear the streets, according to the AP.
National police spokesman Eric Kiraithe had no word on casualties Wednesday, but nurses in Kisumu said at least one man was shot by police and killed.
Violence over the elections, which has in turn fueled ethnic tensions and tribal disputes over land ownership, has left at least 600 people dead and displaced about 250,000.
According to official results, President Mwai Kibaki beat Odinga by 230,000 votes out of 10 million ballots cast. But the electoral chief later said he was pressured to release the results and didn't know who actually won.
Odinga supporters said they would protest until Kibaki and the government acknowledged his re-election was flawed.
The opposition was bolstered Tuesday when lawmakers chose their candidate, Kenneth Marende, to be the new speaker of the National Assembly in a 105-101 vote over a Kibaki supporter.
And Foreign Minister Moses Wetangula said in a Reuters interview that the opposition should transfer its fight from the streets to the parliament.
"You saw us elect a speaker who went through many contested elections but who won narrowly, and the government ... readily accepted the new speaker as validly elected. I would urge my colleagues in ODM (the Orange Democratic Movement) to embrace the same spirit," he said.