All nine people killed in this morning's blast in Istanbul are believed to be foreign, the Turkish President Recep Tayyip Erdoğan has said.
The blast went off in Sultanahmet Square - home to the Blue Mosque - at around 10am local time (8am UK time). The explosion took place near to the Sultanahmet tram stop and Dikilitas, the Obelisk of Theodosius.
A further 15 people were injured in the blast, two of whom are in a serious condition, authorities have confirmed.
The bomber has been identified "from his body parts" as having been born in Syria in 1988, according to Turkey's deputy prime minister Numan Kurtulmus.
There is no word yet who is behind the attack, although Turkey has seen a spate of violence from far left groups, Kurdish militants and Islamic State (Isis).
Images show the moment the blast occurred, right next to the Obelisk.
Turkish police sealed off the square, as crew from the city's ambulance service attended on those caught up in the explosion.
The extent of the damage caused is not yet known, although there are widespread reports of numerous casualties and some deaths.
Reuters is quoting a witness saying there were body parts at the scene, with a police officer corroborating this account.
İşte Sultanahmet ve yaralılar pic.twitter.com/OeCw3cIeje— Ali Fuat Duatepe (@alifuatduatepe) January 12, 2016
The government has issued advice to British tourists currently in Turkey. "If you're in the affected area you should follow the instructions of the local security authorities," it said.
Turkish Prime Minister Ahmet Davutoğlu has reportedly called a crisis meeting in Ankara to discuss the attack.
President Recep Tayyip Erdogan said Turkey was the "top target for all terrorist groups in the region", according to the BBC.
His country, he added, was "fighting against all of them equally".