At least 14 people are dead and 11 are wounded after a bomb exploded on a bus carrying presidential guards in Tunisia.
The explosion went off as the bus travelled down Mohamed V Avenue in the country's capital Tunis.
Dozens of members of the security forces have been killed by extremists since 2011.
There has been no immediate claim of responsibility for the attack.
Several people are believed to be dead after a bus carrying presidential guards exploded in Tunisia, an interior ministry spokesman said.
Security and presidential sources said the explosion was an attack, adding it was not immediately clear whether it was a bomb or an explosive which was fired at the vehicle.
Ambulances rushed from the scene and security forces quickly sealed off the area.
Tunisia has suffered two major attacks this year targeting its tourism industry.
A gunman killed 38 people in Sousse in June and in March gunmen killed 21 in an attack at the Bardo Museum in Tunis. Islamic State claimed responsibility for both attacks.
An explosion has hit a bus carrying military presidential guards in Tunisia, security sources said.
The cause of the blast in the capital Tunis was not immediately clear, but it is believed there are several casualties.
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A Tunisian Interior Ministry official has warned of a plan to attack sites in the capital with car bombs and other devices, according to a state news agency.
The television report on TAP said unidentified militants planned to attack "sensitive sites" in Tunis with car bombs and explosive belts.
It added that police had banned traffic on Bourguiba Avenue in the heart of downtown and nearby streets to prevent attacks. There are also increased police patrols and raids around the capital and its suburbs.
In March and June, gunmen attacked the national museum and a beach resort killing nearly 60 foreign tourists. The attacks were claimed by the so-called Islamic State group.