Bomb blasts ripped through two bars packed with soccer fans watching the World Cup final in Uganda's capital overnight, killing 64 people and signalling a possible Somali Islamist link, police said on Monday.
One American was among those killed in the bombings.
There was no immediate claim of responsibility for the bombings. Al-Qaeda-inspired al Shabaab militants in Somalia have threatened to attack Uganda for sending peacekeeping troops to the anarchic country to prop up the Western-backed government.
One bombing targeted the Ethiopian Village restaurant in the Kabalagala district, a popular night-life spot which was heaving with soccer fans and is popular with foreign visitors. The second attack struck a rugby club showing the match.
Twin co-ordinated attacks have been a hallmark of al-Qaeda and groups linked to Osama bin Laden's militant network.
"Sixty-four are confirmed dead. Fifteen people at the Ethiopian Village and 49 at Lugogo Rugby Club. Seventy-one people are injured," said police spokesperson Judith Nabakooba.
She said 10 of the dead were either Ethiopian or Eritrean. Earlier, the US embassy in Kampala said one American was killed in the bomb blasts.
Revelling one minute in the closing moments of the final between Spain and Netherlands, the bombings left shocked survivors standing among corpses and scattered chairs.
"We were watching soccer here and then when there were three minutes to the end of the match an explosion came ... and it was so loud," witness Juma Seiko said at the rugby club.
Heavily armed police cordoned off both blast sites and searched the areas with sniffer dogs while dazed survivors helped pull the wounded away from the wreckage.
Police said it was possible those behind the attacks on the Ethiopian Village and the rugby club were targeting foreigners.
Ethiopian troops invaded Somalia in 2006 to oust an Islamist movement from Mogadishu. That sparked the Islamist insurgency which still rages.
Uganda, east Africa's third largest economy, is attracting billions of dollars of foreign investment, especially in its oil sector and government debt markets, after two decades of relative stability.
But investors in Uganda and neighbouring Kenya, which shares a largely porous border with Somalia, often cite the threat from Islamic militants as a serious concern.
"The information we have indicates the people who have attacked the Ethiopian Village were probably targeting expatriates," Kayihura said.
"We have evil-minded characters who have been warning us, like the ADF (Allied Democratic Forces), al Shabaab and the Lord's Resistance Army."
The Lord's Resistance Army waged a two-decade war in northern Uganda before crossing into Sudan and further afield into central Africa. In May, Uganda said ADF rebels could be regrouping along the western border with the Democratic Republic of Congo.
In Washington, US National Security Council spokesperson Mike Hammer said Obama was "deeply saddened by the loss of life resulting from these deplorable and cowardly attacks".
"The United States is ready to provide any assistance requested by the Ugandan government," said Hammer.
A senior US administration official said: "We are in contact with our embassy in Kampala and in touch with the FBI regarding government of Uganda requests for assistance."
On Saturday, Somali President Sheikh Sharif Ahmed told Reuters he was worried by the growing number of foreign jihadists joining the ranks of Islamic insurgents and said they posed a growing threat to regional security.
Regional allies are preparing to send an extra 2 000 peacekeepers to Somalia, bringing the total number of African Union troops to around 8 100. Al Shabaab responded by urging Muslims to join a jihad and pledged to attack before being attacked.