Children are suffering as a result of instability and election-related violence in Burundi including three killed in the last five days and dozens forced to flee from school, the U.N. children's agency said Friday.

UNICEF spokesman Christophe Boulierac said one child died as a result of a grenade explosion in Muyinga province, becoming the first child victim outside the capital Bujumbura.

He said in Geneva that a total of eight children have been killed since the violence erupted including a four-year-old hit by a stray bullet to the stomach. His comments were reported on the U.N.'s website.

Burundi "is one of the poorest countries in the world, with one of the highest child malnutrition rates," Boulierac said.

UNICEF calls all levels of Burundian society, including the government, security forces and families to protect children and ensure they are not exposed to violence, arbitrary arrest or unlawful detention, he said.

Burundi has been hit by violence since the April announcement that President Pierre Nkurunziza would run for a third term in presidential elections set for July 15. Protesters are demanding Nkurunziza step down because the constitution limits the president to two terms, but the president's supporters say he is eligible for a third term because he was chosen by lawmakers -- and not popularly elected -- for his first term.

The first round of elections, for parliament, took place on June 29 and a U.N. observer mission concluded Thursday that they were not "free, credible and inclusive."

UNICEF said a second grenade attack took place on a school ground in Bururi province just before voting that day.

There were no victims, but children fled from the school and when they returned they reportedly found military in the school, Boulierac said.