ANKARA, Jan. 12 -- A huge explosion that rocked Istanbul's historic Sultanahmet district on Tuesday was carried out by a suicide bomber of Syrian origin, Turkish President Recep Tayyip Erdogan said.

A total of 10 people were killed, 15 others wounded in the explosion, the president said, adding that foreign citizens were among the dead.

Six German tourists, a Norwegian tourist and a Peruvian tourist were killed in the Istanbul explosion, said the local NTV news channel.

"All I heard was a loud noise and then we saw smoke over there ... I didn't move anywhere, I stayed here and waited till the police came. Soon after ambulances arrived and now the police cordoned off the area," a shop owner nearby told Xinhua.

The Islamic State (IS) group was behind twin suicide bombings in the capital Ankara in October, 2015, that killed 102 people. The group also carried out the Suruc bombing in July, as well as the attacks against People's Democratic Party (HDP) headquarters in Mersin and Adana provinces in southern Turkey, and against HDP rally in Diyarbakir city before June 7 elections, according to Turkish authorities.

Turkey joined the U.S.-led air raids on the IS in July, allowing the coalition to use its bases. Meanwhile, it has also renewed fighting with militants of the outlawed Kurdish Workers' Party following a two-and-a-half-year peace process.

Turkey has stepped up its anti-terror operations across the country since those bombings.