The counter-terrorism branch of the Istanbul Police Department have prevented two terror attacks by PKK group on Thursday, averting great tragedy in Istanbul's Başakşehir and Fatih districts.In the first incident, the counter-terrorism police detected a suspicious pressure cooker left in the street, about 20-metres away from the Dereyolu bridge in the neighborhood of Güvercintepe in Başakşehir district. An improvised explosive device was found to be in the cooker and was immediately disposed by bomb-dismantling specialists.In the second incident, a woman named Güzin T. was caught scouting the area to carry out a suicide attack in front of the Istanbul Police Department building in Fatih district. It was learned that the woman was preparing to carry out a sensational act and was previously adjudged to seven years imprisonment.This wasn't the first planned terrorist attack in Istanbul. Previously, PKK terrorists preparing to carry out an attack in Istanbul's Uzunçayır metrobus station on August 26 were detained by Turkish police, during a routine criminal record check in Istanbul's Kadıköy district.The PKK has carried out numerous attacks in heavily-populated public places. Two terrorists had attacked police at the entrance of Dolmabahçe Palace, a popular tourist site and home to the prime minister's Istanbul offices on August 19. Prior to that, PKK terrorists had also attacked a bus in Turkey's eastern province of Erzurum on August 17, killing a civilian.Turkey has been hit by violence since a suicide bomb attack by a suspected ISIS supporter killed 32 activists in Suruç on July 20.Turkish security forces have arrested hundreds of people with suspected links to ISIS, the PKK, and leftist groups, detaining over 1,300 people across the country, according to a recent statement released by the Prime Minister's Office. According to military sources, 918 terrorists were killed in Turkey's airstrikes against PKK's hideouts and camps in northern Iraq.