The Zanzibar Electoral Commission has declared a victory for the ruling party on the semi-autonomous islands. Earlier in the day, the main opposition party claimed its group had won the October 30 elections.
Supporters of the ruling Chama Cha Mapinduzi decked out in scarves and hats of green and yellow, the party's colors, thronged the streets of Stone Town following the Zanzibar Electoral Commission announcement that the party won Sunday's vote.
The commission says CCM presidential candidate Amani Abeid Karume captured 53.2 percent of the vote, while the presidential candidate for the opposition Civic United Front, Seif Sharif Hamad, got 46.1 percent of the vote.
Earlier, the Civic United Front announced that, according to its count, Mr. Hamad had received almost 51 percent of the vote and the ruling party candidate 49 percent.
Opposition supporters took to the streets in a section of Stone Town in celebration after the Civic United Front announcement.
But about 100 or so police quickly moved in and fired teargas at several points, trying to flush opposition supporters out of the narrow, winding streets.
VOA saw police arresting and beating up several of the protesters and passersby.
The race has been extremely tight, and both sides accuse the other of committing election irregularities.
The past few days have seen police firing teargas and water canons at, and breaking up, groups of opposition supporters, who had taken to the streets to celebrate what they consider an opposition victory. Shops in the historic Stone Town have remained closed during the past three days.
More than 500,000 Zanzibaris were eligible to vote in the October 30 polls. Officials estimate 83 percent of eligible voters cast ballots Sunday.
The Chama Cha Mapinduzi and its predecessors have ruled Tanzania for more than 40 years. The Civic United Front accuses the ruling party of massive rigging in the 1995 and 2000 elections. International monitors and human rights groups had reported serious election irregularities and arrests and unlawful detentions of opposition supporters.
The opposition says it plans peaceful protests if they feel the results do not reflect the will of Zanzibaris.