A major opposition party in Tanzania is accusing police of shooting dead at least seven citizens amid unrest over alleged fraud on the eve of the country’s presidential election. The army was distributing ballot boxes at polling stations designated for advance voting on Monday evening when “Citizens in areas surrounding the polling stations have claimed that these boxes contain ballots already pre-marked,” the party’s statement said. “They accordingly sought to prevent these ballot boxes from being transferred to the polling stations.” Police at first responded with tear gas and the live ammunition, the statement said. The ACT Wazalendo presidential candidate in Zanzibar, Maalim Seif Sharif Hamad, condemned the shootings. He was then arrested Tuesday morning at a polling station as he went to vote, the party said. There was a heavy police and military presence in Zanzibar on Tuesday, with many roads blocked. People reported that internet service had slowed, amid fears that the service would be cut off altogether on Wednesday. Zanzibar has been the scene of deadly abuses by security forces in the past. In 2001, security forces killed at least 35 people and wounded more than 600 while suppressing opposition protests over alleged election fraud, Human Rights Watch reported.