An explosion tore through an apartment block in Istanbul on Monday, killing two men and wounding six others. Istanbul police chief Celalettin Cerrah said the blast had not occurred due to a natural gas explosion as previously reported. Turkey has been set on edge in recent weeks due to a series of blasts in various cities, some of them caused by bombs. "Investigations are continuing but it appears that the explosion happened as they were making something," Cerrah told reporters. Police formed a security cordon around the area, and ambulances and fire engines rushed to the scene, which was a five-storey apartment block in the Zeytinburnu district of the Istanbul.