( CNN ) -- Philippine police and armed forces negotiated the release of five hostages on Tuesday as a tense stand-off with rebels from the Muslim Moro National Liberation Front entered its second day in Zamboanga City in the southern Philippines . `` This morning five people , including four children , who were held hostage in Talon-talon were released by the rebels , '' Mayor Isabelle Climaco-Salazar said in a statement , adding that one policeman was wounded in the thigh in an exchange of fire on Tuesday morning . At least six people were killed yesterday in exchanges of gunfire between the rebels and armed forces . Authorities said it was unclear how many hostages were still being held by the estimated 300 armed Muslim rebels in the blockaded areas of Zamboanga City , a mainly Christian city on the southern coast of Mindanao . Philippine Interior and Local Government Secretary Mar Roxas told a press conference that authorities believed as many as 180 people -- which he described as `` human shields '' -- could be being held hostage . `` These are very soft estimates , '' said Roxas , who flew in from Manila to supervise operations . Hundreds of troops have been deployed to Zamboanga in response to the crisis . `` It 's hard to determine ( whether ) they 're hostages or just residents of the area , but we are taking these numbers quite seriously and that is why the military and the police have exercised restraint . '' Roxas did not say whether the rebels had made any demands . `` There are ongoing talks , formal and informal , in various stages of maturity , '' he said . `` We are also seeking to validate the bonafides of those presenting themselves as mediators so that we are not led astray in these talks . '' An MNLF spokesman told the Philippine Daily Inquirer newspaper that the group was holding 35 hostages . `` We seized them by the roadside so the soldiers wo n't shoot when they see us , '' he said . According to a statement issued by Climaco-Salazar , the crisis began at around 4.30 a.m. local time Monday when government forces clashed with armed rebels heading for the city by boat . Six people , including a policeman , a navy serviceman and four civilians , were killed during the course of these clashes . She said the rebels had planned to march on the city hall . The MNLF , a separatist movement founded in 1971 by Nur Misuari with the aim of establishing an autonomous region for Muslims in this mainly Catholic country , signed a peace deal with the central government in Manila in 1996 -- though some of its members have broken away to continue with a violent campaign . Under the terms of the 1996 agreement , Misuari was named as governor of an expanded Autonomous Region in Muslim Mindanao ( ARMM ) . He served until 2001 . Last month Misuari issued a `` declaration of independence '' for the Moro nation -- referring to Mindanao 's indigenous Muslim population -- after complaining that the MNLF had been left out of a recent wealth-sharing agreement with an another insurgent group , the Moro Islamic Liberation Front ( MILF ) , which has fought for decades to set up an independent Islamic state on the resource-rich island of Mindanao . CNN 's Kathy Quiano and Tim Schwarz contributed to this story .
MNLF rebels release five hostages , four of them children , as stand - off enters second day . An estimated 180 were killed by fighting but it was unclear how many people were hostage . A rebel told local media that the group had been holding 35 hostages . At least six people were killed yesterday in clashes between the rebels and armed forces .