Explosions and gunfire erupted in the capital of the East African nation of Burundi late Thursday, witnesses reported from Bujumbura. It was not immediately clear who was responsible or whether there were any casualties.

Burundi Vice President Yves Sahinguvu, who was in Nairobi for the swearing in of Kenya’s new prime minister, confirmed the outburst after calling Bujumbura. He said explosions took place in the north and south of the city.

Louis-Marie Nindorera, who works for the rights group Global Rights in Burundi, said there had been rumors for days about a possible attack by the rebel National Liberation Front and extra security forces had been in the streets since Wednesday.

“It’s been more than a year _ almost two _ since we have heard such noise,” Nindorera said by telephone from Bujumbura. He said the capital had mostly been quiet since civil war ended in 2006.

A journalist in Bujumbura said mortar shells and small-arms fire could be heard for nearly an hour. He said President Pierre Nkurunziza was out of the capital on an official visit.

The small nation is struggling to recover from the 13-year conflict, which killed more than 250,000 people. The war began when paratroopers from the Tutsi ethnic minority, which had long dominated politics and the military, assassinated Burundi’s first democratically elected president, a member of the Hutu majority, in October 1993.

All of Burundi’s rebel groups, whose fighters are mostly drawn from the Hutus, have signed peace deals except the National Liberation Front.

The guerrilla group has asked for provision immunity before it will hold peace talks with Nkurunziza’s administration, which has governed since democratic elections in 2005.