Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

NAIROBI, Kenya — Police fired tear gas at stone-throwing protesters in some opposition areas Thursday after the start of Kenya's second presidential election since August, reflecting bitter divisions in a country whose main opposition leader urged his followers to boycott the vote.

Violence erupted in Nairobi's Kibera slum and Kisumu, a major city in western Kenya where protesters set fires and blocked roads, and many polling stations didn't open because of security concerns. One Kisumu primary school that saw huge lines of voters when it served as a polling station in Kenya's Aug. 8 election was closed this time around, its gates locked.

"We are not going to vote and we are not going to allow it," said Olga Onyanga, an opposition supporter in Kisumu.

The Morning Rundown Get a head start on the morning's top stories. This site is protected by recaptcha

Voting, meanwhile, proceeded in areas where President Uhuru Kenyatta has support, but fewer voters were turning out in comparison to the August election that the Supreme Court nullified because it found illegalities and irregularities in the election process.

Voters lined up before dawn at a polling station in Kenyatta's hometown of Gatundu and electoral workers prepared ballot papers by flashlight after heavy rains knocked out power to the site.

"Our hope for the country is that whoever emerges the winner will be able to unite the country, which is already torn apart by politicians and politics of the day," said Simon Wambirio, a Gatundu resident.

Voters wait at polling station in Gatundu, Kenya, on Thursday. Siegfried Modola / Reuters

Kenyatta, who was declared the winner in August with 54 percent of the vote, said in a televised address Wednesday that security forces would be deployed nationwide to ensure order, and he urged Kenyans to vote while respecting the rights of those who don't.

Opposition leader Raila Odinga, who got nearly 45 percent in August, said the new vote won't be credible because of a lack of electoral reform and accused Kenyatta of moving a country known for relative stability and openness toward authoritarian rule.

Odinga's call for a boycott resonated strongly in Kisumu, Kenya's third-largest city and an opposition stronghold. He has urged followers to stay away from polling stations because of concerns about a crackdown by security forces. Human rights groups said police killed dozens of people during protests after the August vote; authorities confirmed a smaller number of deaths and said they had to take action against rioters.

Odinga and Kenyatta, who seeks a second term, also faced off in a 2013 election similarly marred by opposition allegations of vote-rigging. The opposition leader also ran unsuccessfully in 2007 — ethnic-fueled animosity after that vote killed more than 1,000 people and forced 600,000 from their homes.