At least five people have been killed after grenades were thrown at a night-club and official residences in Ethiopia's Somali region.
More than 30 people have been wounded in the blasts in regional capital Jigjiga and the nearby towns of Dhagahbuur and Fiiq.
The attacks happened the day before voter registration was due to start in the region for elections next month.
Government officials blame the region's rebel groups for the blasts.
The elections are being held later in the Somali region than in the rest of Ethiopia because of security fears, and because it is difficult to reach the area's nomads.
The attacks had not stopped preparations for the 21 August election, said regional security head Jamiil Haji Mohammed.
His house was targeted, along with that of regional parliamentary speaker Ali Kunai.
Mr Jamil said the attacks had been carried out by the region's Ogaden National Liberation Front (ONLF) rebels.
Four of the deaths occurred when grenades were thrown at a night-club.
Eyewitnesses in Jigjiga said they had heard gunshots before the grenades and other explosive devices were thrown.
In Dhagahbuur, officials confirmed that the child of a
senior official died when a grenade blew up his house.
A land-mine has also exploded under an army lorry but no-one was injured.
The authorities says they have launched a massive manhunt.
Moves to peace?
Information Minister Bereket Simon also vowed that the attacks would not hinder the elections but he said it was too early to say who was responsible.
"This was a terrorist attack that was meant to terrorise people. The election will carry on as normal," he told the Reuters news agency.
The attacks come exactly a week after Prime Minister Meles Zenawi announced his government's willingness to have dialogue with the region's Ogaden National Liberation Front rebels.
The ONLF leaders have also responded favourably to the government's call to dialogue though they are yet to declare any ceasefire.
Election results from the rest of the country show the main opposition coalitions and the ruling party have almost the same number of seats.
The National Electoral Board is investigating allegations of electoral fraud.
Protests against the alleged fraud left at least 36 people dead after security forces opened fire in the capital, Addis Ababa.