The governing party in Cameroon said on Thursday that one of its offices was set on fire in the latest incident of mounting tensions throughout the country over alleged electoral fraud in the October 12 presidential election.

The office of the governing Cameroon People’s Democratic Movement (CPDM) in the western city of Dschang was set ablaze on Wednesday night, the party’s Secretary General Jean Nkuete said in a statement. He added that the party will “initiate legal action against the individuals found guilty of the fire.”

Videos of the burning building were shared widely on social media and in local news outlets. Tensions have been rising in Cameroon after the opposition candidate Issa Tchiroma Bakary claimed victory last week in the presidential election ahead of the release of official results, urging President Paul Biya, 92, the world’s oldest president, to concede.

Biya’s party has rejected Tchiroma’s claim of victory and accused the opposition candidate of trying to disrupt the electoral process. The constitutional court is expected to announce the final official results by October 26.

Tchiroma alleged on Wednesday that there were signs of vote tampering, echoing civil society groups’ earlier reports of “several irregularities” during the poll, including attempted ballot stuffing.

Pockets of protests broke out in several cities over the allegations of election fraud on Wednesday night.

Dozens of protesters in the economic capital Douala, located in Wouri department, erected barricades on the roads and set them on fire while security forces used teargas and water cannon to disperse them. No deaths or injuries have been reported yet.

Some protested outside the office of Elections Cameroon, or ELECAM, the country’s independent electoral management body.

The Prefect of Wouri, Sylyac Marie Mvogo, said the police arrested a score of people who tried to force themselves into the building and allegedly attacked employees.

“We don’t want people taking the law into their own hands; there are competent authorities responsible for handling election matters,” Mvogo, told the state-run radio CRTV.

Analysts have predicted a victory for Biya, 92, as the opposition remained divided and his strongest rival was barred from running in August. Eleven opposition candidates were on the ballot for the Oct. 12 election.

Tchiroma, who is in his late seventies, was a government spokesperson and minister of employment under Biya but quit the government last year to launch his presidential run. His campaign drew large crowds and backing from a coalition of opposition parties and civic groups.

Biya has been in power since 1982, nearly half his lifetime, making him Cameroon’s second president since independence from France in 1960.

During Biya’s decades in power, the Central African nation of nearly 30 million people has struggled with challenges from a deadly secessionist movement in the west and chronic corruption that has stifled economic development despite rich natural resources like oil and minerals.

• An AP report