Fighting between Turkish security forces and Kurdish militants spread on Tuesday, with tanks, helicopters and armored cars deployed after a suicide bombing that killed 37 people in the capital Ankara.

The deadliest violence took place in Diyarbakir, the largest city in mainly Kurdish southeastern Turkey, where Kurdistan Workers Party (PKK) fighters blocked roads and clashed with security forces overnight as a police helicopter flew overhead, witnesses said.

One police officer and three militants were killed in Diyarbakir and a second police officer was killed in the town of Nusaybin, where the PKK launched an attack, security sources said. […]