Gunmen have attacked Tunisia's parliament, killing eight people and seizing hostages in a nearby museum, said officials.
Gunfire was heard at the parliament building, and local media has reported casualties.
Seven tourists and one Tunisian have been killed in the attack, reported Tunisia Live, citing a government official.
There are unconfirmed reports in local media that Spanish, Italian and UK nationals are among those killed.
"We are urgently looking into the serious situation in Tunisia," said a Foreign and Commonwealth Office spokesperson.
Hostages have been seized at the Bardo Museum, which shares its grounds with the country's parliament buildings, a spokesman for the country's interior ministry told local media.
Pictures on social media purportedly taken by hostages seem to show up to 30 hostages gathered in the museum.
Special forces were deployed to storm the museum, and casualties have been taken to the hospital Charles Nicolle.
Tunisian state television quoting the ministry of the interior reported that the attackers are dead.
Footage on Tunisian television shows hostages fleeing the museum, given cover by Tunisian special forces.
An interior ministry spokesman said that security forces had surrounded two militants who were inside the museum, with grenade explosions having been heard.
Mohamed Ali Aroui, a government spokesman, has told reporters: "A terrorist attack targeting the Bardo Museum [was carried out by] two or more terrorists armed with Kalashnikovs. There are eight victims [including] seven foreigners. The majority of tourists were evacuated. Anti-terrorist units have entered the museum."
Independent radio station Radio Mosaique reported that three men dressed in military-style fatigues had launched the attack.
Tunisian armed forces are currently fighting Islamist groups which emerged after the country's 2011 revolution, with thousands of Tunisians believed to have left the country to fight for Islamist groups in Syria and Iraq.