ISTANBUL — A large explosion rocked a square in Sultanahmet, the historic central district of Istanbul, on Tuesday morning, killing at least 10 people and wounding 15 others. President Recep Tayyip Erdogan said a Syrian suicide bomber was behind the attack, the latest in a series of terrorist assaults on Turkey.
The explosion, which occurred around 10:15 a.m., killed and wounded both Turks and foreigners, Mr. Erdogan said in a televised address from Ankara, the capital.
“Turkey is the first target of all terrorist groups,” Mr. Erdogan said. He mentioned the Islamic State and Kurdish separatists as threats to the nation’s security but did not specifically blame either for the attack on Tuesday.
A deputy prime minister, Numan Kurtulmus, said at a news conference that the assault had been carried out by a Syrian man born in 1988. “The blast is an extension of proxy wars that have been going on in Syria for the last five years,” he said.
Six Germans, one Norwegian and a Peruvian were among the wounded, the Dogan News Agency reported.
“I was in the basement checking the stocks when I heard a huge bang, and the whole building shook,” said Fehmi Ozyurt, a local leather vendor. “We all ran out and could see bodies on the floor, but we were too scared to get close in case there was another explosion. We’ve been through this before in Sultanahmet, so we expect the worst — that it’s a suicide bomber again.”
Last January, a suicide bomber, a Russian citizen with possible ties to the Islamic State, blew herself up at a police station in the Sultanahmet area, killing an officer. But the attack on Tuesday occurred at one of the most heavily trafficked districts in the historic city, steps from monuments commemorating the three empires — Roman, Byzantine and Ottoman — of which the former Constantinople, now Istanbul, was the capital.
More than three hours after the explosion, a group of waiters stood in shock outside a nearby meatball restaurant.
“I don’t know what to say — I guess we were expecting this, but not an explosion this big,” said one of the workers, who gave his name only as Ibrahim, his eyes fixed on the Blue Mosque, a renowned early 17th-century landmark.
On a usual day, the restaurant would be bustling with customers, with lines forming outside. But after the explosion on Tuesday, there was barely a visitor in sight.
“Tourism had already dried up after last year’s explosion, but after this it’s game over,” said Ayse Demir, 36, a shopkeeper at a local arts and crafts shop. “No one is going to risk their lives for shopping and history.”
By Tuesday afternoon, most of Sultanahmet’s historic square had been cordoned off as the police investigated. Helicopters hovered and the public was asked to leave the area.
Some police officers blocked journalists from entering the square and asked them to refrain from taking photographs and video because of a nationwide broadcast ban.
Sultanahmet is home to some of Istanbul’s most visited monuments, including a Byzantine-era former hippodrome, or racetrack; the Hagia Sophia, a sixth-century Greek Orthodox basilica and now a museum; the Blue Mosque; and the Topkapi Palace, built by the Ottoman sultans.
Photographers took images of numerous bodies around the base of an obelisk and of police officers with helmets and shields rushing to the scene. The obelisk, which was carved around 1490 B.C., was brought to the city in A.D. 390 by the Roman emperor Theodosius.
After a briefing from Efkan Ala, Turkey’s interior minister, Prime Minister Ahmet Davutoglu called an emergency meeting of ministers in Ankara to discuss the situation. Not long after, Mr. Erdogan made his televised address.
Mr. Erdogan’s remarks included an extended critique of foreign scholars and writers, including Noam Chomsky, for criticism of his government.
“Pick a side,” Mr. Erdogan said. “You are either on the side of the Turkish government, or you’re on the side of the terrorists.”
After the attack on Tuesday, the German Foreign Office issued a statement warning tourists to stay away from public spaces. “Travelers in Istanbul are urgently advised to temporarily avoid crowds, even on public squares and outside tourist attractions,” the statement said. “One has to continue to expect political tensions, violent confrontations and terrorist attacks across the country.”
More than 5.4 million Germans visited Turkey last year, accounting for 15 percent of all visits by foreigners.
The explosion in Sultanahmet was the latest in a string of terrorist attacks in Turkey. The Islamic State, which controls a significant portion of territory in neighboring Syria, has been targeting Turkey, where violence has surged since a cease-fire broke down in a decades-long fight between the Kurdistan Workers’ Party, or P.K.K., and the Turkish government.
In June, two people were killed at a rally in the predominantly Kurdish city of Diyarbakir, in southeastern Turkey.
And in October, suicide bombers hit a lunchtime peace rally in Ankara, killing about 100 people. No one has claimed responsibility for that attack.
Esra Ozyurek, a political anthropologist at the London School of Economics, said that Tuesday’s attack did not immediately appear to resemble those three. Many analysts have attributed those attacks to the Islamic State, saying the terrorist network was trying to touch off a civil war in Turkey.
“This bombing is different from the bombings in Diyarbakir, Suruc and Ankara, where Islamic State-affiliated bombers targeted groups of pro-Kurdish or pro-peace citizens who are in opposition to the government,” Dr. Ozyurek said. “In this one, the target is unclear.”
She added: “This explosion will at the least deeply affect the tourism industry, which was already hurting.”