Pickup trucks with members of the security forces roamed the capital's streets on Tuesday. The men were carrying sticks, riot shields, assault rifles and one had a rocket-propelled grenade launcher.
Black smoke rose into the sky from neighbourhoods right across Lome.
Riot police were deployed as youths hastily pu up roadblocks in several areas. Elsewhere, scared residents scurried for cover, rapidly emptying streets.
Earlier, Togo's ruling party candidate Faure Gnassingbe was declared the winner of the West African country's presidential election on Tuesday with 60.22% of the vote, according to provisional results from the electoral commission.
Opposition activists had vowed to launch violent protests if Gnassingbe were declared winner, saying the election had been marred by irregularities, which invalidated the result.
Faure Gnassingbe won 1.4 million votes, said electoral commission chairwoman Kissem Tchangai Walla.
Faure Gnassingbe was declared
winner in the election
Main opposition candidate Bob Akitani took 38%, or 841,000 votes, she said.
Gnassingbe and a senior figure from Akitani's party had agreed on Monday in nearby Nigeria that whoever won would form a government of national unity.
Walla said the results had to be be certified by Togo's constitutional court in coming weeks. The results do not include ballots cast at about 700 polling stations nationwide that were destroyed during election violence on Sunday.
Togo tumbled into crisis on 5 February, when President Gnassingbe Eyadema died of a heart attack, ending his 38-year rule, which made him Africa's longest-serving leader.
Loyalists in his army named his son the new leader, but Faure called the election and stepped down under intense pressure from other African nations that branded the succession a coup d'etat.