Three Turkish security personnel were killed in an attack by militants from the outlawed Kurdish Workers' Party (PKK) here on Thursday, said a Turkish General Staff statement.The security forces were accompanying soldiers back from their annual leave, when they were attacked by a group of PKK rebels in the province of Sirnak, Xinhua reported, citing the statement.The attack came amidst escalating tensions in Turkey as the PKK staged several retaliatory offensives against the security forces, after the government's military operations targeted PKK posts both in Turkey and northern Iraq.