Burundian President Pierre Nkurunziza has died of heart failure, the government said Tuesday in a post from its official Twitter account.

"The Government of the Republic of Burundi announces with great sadness the unexpected death of His Excellency Pierre Nkurunziza, President of the Republic of Burundi following heart failure on June 8, 2020," the post said.

An evangelical who believed he was chosen by God to rule the East African nation, Nkurunziza came to power in 2005, when he was selected by parliament. 
His controversial and ultimately successful bid for a third term in 2015 plunged the country into crisis.

Violence left at least 1,200 people dead, displaced hundreds of thousands and the authorities carried out a sustained crackdown on the opposition and media.
His death comes on the heels of elections on May 20 in which his hand-picked successor, Evariste Ndayishimiye, secured a seven-year term as president -- a result confirmed by the constitutional court last Thursday.

Ndayishimiye was due to be sworn in in August. 
A statement from Burundi's presidency on Tuesday said Nkurunziza was hospitalised over the weekend and that his health "abruptly changed" on Monday.
It said the country would observe seven days of mourning beginning Tuesday.

Having ruled Burundi with an iron fist for 15 years, many observers say Nkurunziza's influence will still linger for a while after the May 20 election.

In 2018, Burundians voted in a referendum that could have extended Nkurunziza reign until 2034. He, however, surprised many when he announced he would not contest in the 2020 election.

He served three terms, the third of which sparked lengthy unrest in the country.