Bangkok , Thailand ( CNN ) -- Sixteen insurgents were killed during a fierce battle after they attacked a military base in a restive area of southern Thailand early Wednesday , authorities said . Thai military officials said 50 to 60 heavily armed attackers tried to storm the navy base in the province of Narathiwat under cover of darkness , but navy personnel had been forewarned and fought the insurgents off in an intense , hour-long firefight . It appeared to be the latest flare-up in a worsening conflict between government forces and Muslim separatists in southern Thailand in which more than 5,000 people are believed to have been killed since 2004 . Although Thailand 's population is overwhelmingly Buddhist , Muslims make up a large percentage of the population in the country 's three southernmost provinces , near the border with Malaysia . Parts of those provinces have been under an emergency security decree for years , but analysts say the Thai military is struggling to deal with the militants . `` Insurgents have withstood and adapted to the military 's tactics , growing more proficient and daring in the process , '' the International Crisis Group , a nonprofit organization that provides analysis and advocacy on conflicts around the world , said in December . Meanwhile , successive Thai governments `` have opted to muddle through South East Asia 's most violent internal conflict , '' the group said in a report on the conflict , citing `` bureaucratic turf battles and a bitter national-level political struggle . '' Well-armed attackers . The insurgents who carried out the attack Wednesday were armed with military-grade weapons , including laser-guided rifles and hand grenades , said Col. Pramote Promin , a spokesman for the Thai military . Some of the roughly 100 Thai navy personnel on the base were wounded in the fighting , he said , but none were killed . The military had received a tip about the attack and was `` on full alert '' when it happened , he added . The military is now trying to track down wounded insurgents who fled from the clash , Pramote said after visiting the area . He said that after a count at the base , the number of insurgents killed stood at 16 , one fewer than the initial total he gave earlier Wednesday . There was no word Wednesday from the elusive Muslim separatists , who do n't usually claim responsibility for attacks they carry out . Unrest linked to arrest . On Sunday , a roadside bomb in Yala province , which is next to Narathiwat , killed five Thai soldiers , authorities said . Lt. Gen. Dithaporn Sasasmit , a spokesman for the Thai internal security operations command , said recently that the latest insurgent violence is related to the arrest of one of the separatist leaders in January . `` Every time when authorities can arrest or conduct raid operations to prevent possible attacks , they would try to show off and create some situations , '' Sasasmit said . Human Rights Watch last year said that in 2011 , insurgent groups targeted teachers they saw as symbols of state efforts to undermine Malay Muslim identity . The group said that Thai security forces have faced few consequences for abuses against Muslims .
NEW : The Thai military says 16 insurgents were killed , one fewer than previously stated . The heavily armed militants attacked under cover of darkness , military officials say . But the Thai navy personnel in the base were ready after receiving a tip , the officials say . Muslim separatists in southern Thailand have been fighting government forces for years .