Authorities in Uganda said more than 60 people were killed and scores more wounded in two separate bomb explosions in the capital, Kampala, late Sunday.
Police said the first blast took place at an Ethiopian restaurant, while the second explosion occurred at the Kyaddondo Rugby grounds.
Both explosions took place as residents watched the final game of the FIFA 2010 World Cup from South Africa.
Princess Kabakumba Matsiko, Uganda?s Minister of Information, told VOA the casualty figure could go higher.
?There is a bomb blast at two sites, one at Kabalagala. This is on the outskirts of Kampala, and about 13 people died. And, then, at Kyaddondo Rugby Club, this is on Jinja Road, about 30 people died and some were injured. But, the casualties might be more. We are still compiling the figures,? she said.
No one claimed immediate responsibility for the attacks. A police official said he suspected the Somali Islamist militia al-Shabab might be behind the attack, which would make it the group's first attack outside of Somalia.
Journalist Alex Atuhaire, editor of the Daily Monitor said Al-Shabab had threatened revenge for Uganda?s peacekeeping role in Uganda.
?Apart from the African Union summit coming up, there has already been warning that the al-Shabab will make a revenge of the Ugandan military?s activities in Somalia and cause havoc here,? Atuhaire said.
The 15th Ordinary Session of the African Union summit is scheduled to be held in the Ugandan capital from 19th to 27th July.
Information Minister Matsiko said every African Union summit site in Kampala has been secured.
?I can assure you security is guaranteed. All the systems have been put place, and the venues for the AU summit have secured under 24 hour surveillance,? Masiko said.
In the Somali capital, Mogadishu, a commander for al-Shabab told the Associated Press he was happy with the attacks in Uganda, but refused to confirm or deny whether the group was responsible.
In Washington, White House officials said President Barack Obama was "deeply saddened" by the "deplorable and cowardly" attacks.
President Obama and Secretary of State Hillary Clinton said the United States is ready to provide any assistance requested by the Ugandan government.
The U.S. embassy confirmed at least one American was killed in the blasts, and media reports said at least three other Americans were wounded.