KAMPALA, Uganda (AP) — An official says a prominent opposition figure has been detained following violent clashes Monday night that allegedly started when the president's motorcade was pelted with stones.

Captain Jimmy Omara, a spokesman for the Special Forces Command, said lawmaker Kyagulanyi Ssentamu spent the night in a police cell in the northwestern town of Arua.

Ssentamu and other politicians, including President Yoweri Museveni, were in Arua to campaign in a by-election to choose a lawmaker.

Ssentamu, a popular pop star whose stage name is Bobi Wine, said on Twitter Monday night that his driver was shot dead by the police "thinking they've shot at me."

Police spokesman Emilian Kayima said an unidentified man had been killed as the security forces tried to "calm down the situation" after Museveni's convoy came under attack.