Faure Gnassingbe supporters celebrated the news their leader had won the presidential election with 60% of votes.
News of their defeat brought opposition activists onto the streets of the capital, Lome, and a riot ensued.
The city has been shaken by violent protests since Mr Faure Gnassingbe first tried to take power in February through a simple parliamentary vote.
Riot police moved in to quell Tuesday's violence using rubber bullets and stun grenades.
Suspected looters were beaten with canes as the security forces spread out in the streets.
The United States began evacuating non-essential staff at its embassy as the scale of the unrest across Lome became apparent.