Investigators in Uganda say they have arrested the masterminds behind the twin bomb attacks last month that killed 76 people in Kampala.  

The four Ugandan men admitted their involvement in the attacks during a news conference Thursday.  The bombings targeted a restaurant and a club where people had gathered to watch the World Cup football final.

The leader of the attackers said he wanted to kill Americans out of religious conviction.  He said he was a member of al-Shabab, the AL-Qaida linked militant group which claimed responsibility for the double suicide blasts.  

Authorities in Uganda and Kenya have already detained a number of other people they believe were connected to the bombings.  Late last month, a Ugandan court charged three people after arresting about 20 others in connection with the attacks.   

Somali militant group al-Shabab had never mounted a major terrorist attack outside Somalia.  

The group said it was avenging the deaths of Somali civilians at the hands of the African Union peacekeeping force in Somalia.  Ugandan troops make up the bulk of that force, which supports the Somali government.  Al-Shabab has warned that more attacks will follow.

Some information for this report was provided by AP and AFP.