Turkish soldiers killed four suspected Islamic State militants Saturday and authorities detained 11 people demonstrators a day before leaders of the G-20 group of economic powerhouses meet for a summit overshadowed by the slaughter in Paris.

The Anadolu Agency said two cars believed to be carrying IS militants approached an armored military vehicle, ignored warnings to stop and opened fire on the soldiers. The soldiers responded, killing four militants inside one of the cars; the second car escaped, Anadolu said.

The incident occurred close to a military border outpost near the town of Oguzeli, in Gaziantep province — some 700 kilometers (more than 400 miles) east of the Mediterranean coastal resort where U.S. President Barack Obama and other leaders of the world's top 20 economies will meet Sunday and Monday. Some of the leaders began arriving on Saturday.

Police arrested four demonstrators outside a domestic flights terminal at Antalya airport, near the conference venue, Anadolu said. "Murderer U.S. get out of the Middle East," said placards held up by protesters, the private Dogan news agency said.

Seven other demonstrators were detained in Istanbul after protesting outside the German and British consulates.

The war in Syria — Turkey's neighbor — and Islamic extremism had loomed as major items on the G-20 agenda, but that gained greater urgency following the terror attacks in Paris. The Islamic State group claimed responsibility for the deadliest attacks in France since World War II.

In a show of grief and solidarity with the victims, officials said Saturday that no music will be played at dinner or other events during the two-day gathering at the secluded seaside resort of Belek, near Antalya. French President Francois Hollande canceled his trip to the meeting.

Turkish President Recep Tayyip Erdogan, whose guests include U.S. President Barack Obama, Russia's Vladimir Putin and China's President Xi Jinping, has insisted that the perils posed by Syria are casting a shadow on world security and stability, and therefore on the global economy.

The spillover from Syria certainly poses a threat to Turkey. The IS group is blamed for two massive bombings — one in the Syrian border town of Suruc and in the capital Ankara — that killed about 130 people in July and October.

Turkish security forces have carried out sweeps against suspected IS militants in the weeks leading to the summit meeting, detaining dozens of people, including some 20 suspects who were nabbed in and around Antalya.

European governments are talking to Turkey about stemming the deluge of refugees spilling into Europe. The European Union has offered cash and promises of progress on Turkey's bid to join the club, in exchange for a greater effort to keep the migrants in Turkey. More than 2 million refugees are already in Turkey, which has spent more than $8 billion since 2011 caring for them.

"Of course the economy is the G-20's real reason for being but in our day it is not possible to consider the economy separately from politics, social developments and security," Erdogan said recently. "The Syrian issue has created humanitarian dimension, a terror dimension and economic impact."