Philippine military helicopters on Monday fired rockets at Muslim rebels who were holed up in areas of a major city on the southern island of Mindanao . The rebels have been holding scores of people hostage in Zamboanga City for the past week in a crisis that authorities estimate has left as many as 61 people dead and more than 150 wounded . No truce : Army , Islamic militants fight on in Philippines . Intense exchanges of gunfire continued to take place Monday as military officials said they were trying to tighten the noose around rebel-held areas . Two MG-520 attack helicopters from the Philippine Air Force fired rockets at rebel positions over a roughly 20 minute period in the early afternoon , the official Philippine News Agency reported , citing military officials . The recent violence has largely paralyzed Zamboanga , a usually bustling trading hub on the southwestern tip of Mindanao , and displaced more than 60,000 people . The crisis has increased fears of instability in a region where the central government is pursuing a new peace plan after decades of unrest . President Benigno Aquino III and other top Philippine officials are overseeing the response in Zamboanga , a mainly Christian city . The Philippine armed forces are carrying out an operation to try to `` constrict '' the rebels , who came ashore last Monday , said military spokesman Lt. Col. Ramon Zagala . He described the operation as `` delicate , '' as the troops try to avoid harming hostages and any other civilians caught in the parts of Zamboanga where the rebels are holed up . The rebels now hold one third of the territory they had last week , before the military began its effort to squeeze their positions last Friday , Zagala said . The armed forces switched to a more offensive approach after the rebels fired mortars into civilian areas , he said . More than 100 hostages . Military officials say they believe that slightly more than 100 rebels remain active in Zamboanga and that they are still holding more than 100 people as a human shield . Some hostages and other civilians trapped in the rebel-held zone have managed to flee during outbursts of fighting over the past week . Security forces estimate that they have killed 51 rebels , although only 21 bodies have been recovered . A further 48 rebels have been captured and nine have been wounded , Zagala said . The violence has killed six members of the Philippine security forces and four civilians , he said . The number of people estimated to have been wounded , including rebels , stands at 157 . The unrest in Zamboanga has closed schools and businesses . Hundreds of houses of houses have caught fire during the fighting . Authorities have accused the rebels of deliberately starting the fires . The rebels are a faction of the Moro National Liberation Front ( MNLF ) , a separatist movement founded in 1971 by Nur Misuari with the aim of establishing an autonomous region for Muslims in the mainly Catholic Philippines . The MNLF signed a peace deal with the central government in Manila in 1996 , but some of its members have broken away to continue a violent campaign . 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 another insurgent group , the Moro Islamic Liberation Front , which has fought for decades to set up an independent Islamic state on resource-rich Mindanao .
The military carry out a surprise attack on rebel positions in Zamboanga City . The armed forces are trying to ` ` constrict '' the rebels ' " , a spokesman said . Police estimate that more than 60 people have been killed during the crisis . The unrest in and around the port city has displaced more than 60,000 people .