Zambian authorities sealed off the court grounds where an opposition leader is preparing to challenge the outcome of Aug. 13 elections, as the deadline for filing a petition draws near.

Zambia’s president extended a commanding lead in the nation’s election, though a shootout at the home of the main opposition leader raised tensions in Africa’s second-largest copper producer.

Zambia’s electoral commission cited reports of violence as it halted vote counting in the southern African nation’s general election, while the leading opposition candidate warned that delaying the results could mask foul play.

At the University of Zambia, students who’d queued since 2 a.m. shouted a countdown to the start of Thursday’s general elections and rushed through the door to decide whether to give President Hakainde Hichilema a second term.