(KUNA) -- At least 18 guerrillas of the Liberation Tigers of Tamil Eelam (LTTE) and two civilians were among 21 persons killed in separate clashes in Sri Lanka during the last 24 hours. Sri Lankan Army men Wedenesday killed 10 LTTE rebels in the country's Mannar district while three rebels were killed in Weli Oya area of the island nation Tuesday, news agencies reported. Five LTTE rebels were killed at Thoppigala in Sri Lanka's Eastern Province Tuesday, the news agencies said. A Sri Lankan paramilitary security personnel was killed at Eravur in Eastern Province this morning in a shootout with LTTE, the news agencies reported. Two Tamil civilians were also killed last night in Vavuniya in Northern Sri Lanka by unidentified killers, the news agency said.