Gunmen dressed in military fatigues burst into a Burundi bar and shot dead three ruling party activists before torching the local party office, police and local officials said Tuesday.

“They tied them up on the ground, then killed them with automatic weapons,” said a local official, speaking on condition of anonymity.

Police confirmed the attack, which took place late Sunday in the eastern Gisuru region, some 250 kilometres (155 miles) east of the capital Bujumbura.

The five gunmen — who police spokesman Pierre Nkurikiye called “bandits” — then left without stealing anything to set fire to a nearby office of the ruling CNDD-FDD party.

The attack is the latest violence in Burundi, following heavy clashes between the army and rebels last week in which over 100 insurgents were reportedly killed.

The army has said the rebels had planned a major offensive to destabilise the country ahead of elections due in May and June.

Burundi, a small nation in Africa’s Great Lakes region, emerged in 2006 from a brutal 13-year civil war and its political climate remains fractious ahead of the polls.

President Pierre Nkurunziza, in power since 2005, is expected to run for a third term in office despite opponents’ claims that this would violate Burundi’s constitution.

Onesime Nduwimana, spokesman of Nkurunziza’s CNDD-FDD party, condemned the “political” attack on the bar.

“It is very serious, because it is a crime that is certainly political in nature,” Nduwimana told AFP.

“We believe those who committed this cowardly crime belong to the extremist fringe of the Burundian opposition, with the aim of sabotaging the 2015 elections.”

While the identity of the gunmen is not known, Nduwimana said he feared they wanted to destabilise the country by “sowing hatred” and provoking revenge attacks by the Imbonerakure, a controversial youth wing of the CNDD-FDD.

“We ask that those responsible for these crimes are prosecuted wherever they are,” Nduwimana said.