A bomb exploded on a bus transporting Tunisia's presidential guard in central Tunis Tuesday killed at least 14 people and wounding 11, the interior ministry said.
The explosion, described as an "attack" by presidential spokesman Moez Sinaoui, struck on the capital's Mohamed V Avenue, a ministry official told AFP.
While there was no immediate claim of responsibility, Tunisia has been plagued by Islamist violence since the 2011 overthrow of longtime dictator Zine El Abidine Ben Ali.
Two attacks earlier this year claimed by the Islamic State group targeted foreigners -- at the National Bardo Museum in March, killing 21 tourists and a policeman, and at a resort hotel in Sousse in June, killing 38 tourists.
Dozens of members of the security forces have also been killed by extremists since 2011.