Istanbul Police arrested seven more suspects Thursday in connection to a bomb-laden van that was discovered in the city Wednesday.

Before the latest round up, two suspects were arrested in Istanbul's Fatih and Bahçelievler districts. Authorities have claimed that the suspects were plotting to carry out a bomb attack in the city, though it was not clear if the target would be Bahçelievler or some other district.

The van, loaded with 60 kilograms of RDX explosives, was discovered as the leaders of Muslim countries gathered for an Organization of Islamic Cooperation summit in Istanbul. The PKK, which is listed as a terrorist organization by Turkey, the U.S. and the European Union, resumed its armed campaign against the Turkish state in July 2015. Since then, it has been responsible for the deaths of roughly 1,200 security personnel and civilians. The terrorist group mainly targets southeastern and eastern regions of Turkey in its campaign of violence. It is also these regions wherein it recruits militants. It occasionally carries out attacks in western cities.