Unidentified assailants launched coordinated attacks on three military camps in Burundi's capital Bujumbura Friday early morning.

The attack left three soldiers and 12 attackers dead, the Burundian army said. Twenty other attackers were captured along with arms and ammunition, according to BBC News.

United Nations Secretary-General Ban Ki-moon condemned the fatal attacks, saying that such acts of violence can lead to further destabilization of the situation in crisis-torn Burundi.

"The Secretary-General urges the leadership of these groups and the national authorities to refrain from any further escalation of violence or retaliation and stresses that anyone responsible for ordering or committing human rights violations will be held individually accountable," the U.N. chief's spokesperson said in a statement.

The U.N. warned Tuesday that mounting violence in Burundi could turn into genocide.

"I am not saying that tomorrow there will be a genocide in Burundi but there is a serious risk that if we do not stop the violence this may end with a civil war and following such a civil war anything is possible," said Adama Dieng, a special U.N. adviser for the prevention of genocide, according to AFP.

Zeid Ra'ad Al Hussein, U.N. High Commissioner for Human Rights, also expressed concern over the increasing incidents of targeted attacks in the east African country.

"The number of people killed in Burundi continues to steadily grow, as does the number of people forced to flee their homes. Targeted attacks are also on the rise and are now taking place in neighbourhoods of Bujumbura that were previously considered to be safe," Al Hussei said, according to CAJ News Africa.