The Istanbul Security Service chief has ordered to down helicopters, and a total of 1,800 special police were brought to the city, reported Anadolu news agency of Turkey.

These special police forces are patrolling all key facilities and streets of Istanbul, and special vehicles also have been brought to the city.

According to police sources of the abovementioned news agency, the Istanbul Security Service chief has instructed to down, without warning, all helicopters that conduct unauthorized flights. 

Security measures are set in Istanbul after a special operation during which eleven persons, who are suspected of orchestrating the recent riots, were arrested at Sabiha Gökçen International Airport in Istanbul.