Ugandan police forces and security agencies are seen outside one of Kampalas most prominent mall on September 13, 2014. Local authorities uncover a “terrorist cell” run by the Somali militant group al-Shabab, and U.S. Embassy in Uganda has told citizens to seek shelter. (Isaac Kasamani/AFP/Getty Images)

The U.S. Embassy told Americans in Uganda to seek safety on Saturday, warning that local authorities had uncovered a “terrorist cell” run by Somali militant group al-Shabab, which they believed was planning an imminent attack.

The embassy posted a statement on its Web site that said it was not aware of specific targets but that the authorities had increased security at key sites including Entebbe International Airport. “We remain in close contact with our Ugandan counterparts as investigations continue into what appears to have been planning for an imminent attack,” the statement said.

The al-Qaeda-aligned militant group warned of revenge against its enemies after its leader, Ahmed Godane, was killed this month in a U.S. airstrike on his encampment in Somalia.

At a news conference later Saturday, Ugandan police said they had seized explosives and arrested an unspecified number of foreigners after foiling an attack in central Kampala. But Fred Enanga, a Uganda police spokesman, declined to say whether he believed the cell was connected to Islamist militants al-Shabab or to name the nationalities of those detained. The police said it was increasing security at hotels and other public places.

Uganda, as one of the countries that contribute forces to an African Union peacekeeping mission battling al-Shabab in Somalia, has suffered militant attacks in recent years, and the Islamist militants have threatened more.

The U.S. Embassy also posted a message on Twitter, telling Americans in Uganda to stay at home or proceed to a safe location while authorities completed operations against a suspected cell in Kampala. The embassy has said Uganda faces a “continued threat” and has issued other alerts during the year about possible attacks.

Al-Shabab claimed responsibility for the attack on the Westgate shopping mall in neighboring Kenya a year ago, in which 67 people died. And in 2010,
al-Shabab bombed sports bars in Uganda where people were watching the soccer World Cup on television.

— Reuters