The bombs struck at 10:30 p.m. local time in the middle of the match between Spain and the Netherlands under way in South Africa, hitting a popular Ethiopian garden restaurant and a large rugby field in a different Kampala neighborhood where hundreds of people had massed to watch the game.

Ugandan police officials said they suspected that theShabab, a militant Islamic group in nearby Somalia, might have been behind the bombings. If so, it would be that group’s first attack outside Somalia. But the police said it was premature to draw conclusions.

Local journalists at a major hospital said an unidentified number of American citizens were among the wounded.