The deputy mayor of Istanbul's Sisli district, Cemil Candas, was shot in the head on Monday by an unknown assailant. He is in a critical condition, according to Turkish news channel NTV. The shooter broke into Candas' office and opened fire, The Telegraph reported.

It has yet to be ascertained whether the shooting is related to the attempted military coup in Turkey, in which 294 people were killed and more than 1,400 others injured. Security was heightened in Istanbul since the unrest ensued late on Friday, July 15. More than 6,000 people have been arrested so far.

President Recep Tayyip Erdogan called the foiled bid to overthrow the government an "act of treason", while Prime Minister Binali Yildirim said those behind the incident will "pay a heavy price".