COLOMBO (Reuters) - Sri Lanka on Monday deployed soldiers to quell unrest sparked by a fear of nighttime prowlers known as "Grease Devils", after at least five died over the past two weeks in a wave of vigilantism and clashes with police across the island nation. Sri Lanka's army also set up a new brigade in Kinniya near the eastern port of Trincomalee, where thousands of angry people last week besieged a government office after fighting with the navy in pursuit of suspected "grease devil". The increased deployment came a day after a mob killed a police officer in the northwestern town of Puttalam.