Kenyan President Uhuru Kenyatta has been sworn in for a second five-year term.
It took place shortly before riot police teargassed the convoy of opposition leader Raila Odinga, who promised supporters he would be sworn in himself on 12 December.
Such a move would only deepen divisions opened by the extended election season in Kenya, a Western ally in a volatile region.
Months of acrimonious campaigns and sporadic clashes have already blunted growth in east Africa's richest economy.
At a lavish inauguration attended by the heads of many African nations, Mr Kenyatta did his best to paint a picture of a country moving beyond that divide.
"The elections are now firmly behind us ... I will devote my time and energy to build bridges," he told a rapturous crowd as he was sworn in for a second, five-year term in a sports stadium in the capital of Nairobi.
But, he warned, Kenyans needed to "free ourselves from the baggage of past grievances, and ... keep to the rule of law".
Such words may ring hollow to citizens accustomed to the government ignoring reports on corruption from the country's auditor-general and documentation of hundreds of extrajudicial police killings every year from human rights groups.
Mr Kenyatta won a repeat presidential election in October that was boycotted by opposition leader Raila Odinga, who said it would not be free and fair.
The Supreme Court nullified the first presidential election, in August, over irregularities.
Last year, Mr Kenyatta angered many Kenyans by saying he wanted to tackle corruption but his "hands are tied".
His government has also promised to improve police accountability, but an independent watchdog has only ever managed convict two officers of murder despite thousands of brutality complaints.
Today, at least one supporter of Mr Odinga was killed and three others were injured, a Reuters witness said. Other witnesses said the man had been shot by the police.
A statement from Mr Odinga said five people were shot, including his daughter's driver.
Less than an hour after Mr Kenyatta spoke, Kenyan national television carried pictures of riot police swinging clubs at civilians with their hands up.
"I didn't hear him (Kenyatta) say a single word on corruption and how he's going to fight it. I didn't hear anything on justice," said prominent an anti-corruption campaigner.
"When he says that there's the rule of law, his actions and the actions of his government show there's no rule of law."