Updated

BUJUMBURA, Burundi (AP) — An official says a grenade has exploded near the offices of the European Union election observer mission in Burundi hours before residents in the East African nation began voting for president.

A spokesman for the EU mission says there was no damage to the office when the blast went off late Sunday.

Burundi began voting for president Monday. The nation has seen more than 40 grenade attacks that have killed five people in the last several weeks.

Tensions have been rising since early June when six opposition candidates pulled out of the presidential election, citing intimidation and rigging by the government in previously held district elections.

Incumbent President Pierre Nkurunziza is the lone candidate in Monday's election.