(CNN) -- Muslim Moro National Liberation Front rebels were holding at least 180 hostages in Zamboanga on the Philippine island of Mindanao as troops continued to pour into the embattled city, Philippine state media said Wednesday.
There are also reports that the breakaway group seized between 30 and 37 additional hostages in the city Wednesday morning, said PNA, the state news agency.
Philippine Interior and Local Government Secretary Mar Roxas had earlier told a news conference that about 100 hostages were in the hands of the MNLF rebel forces in Zamboanga.
Roxas said almost 13,000 people had been evacuated amid fighting between government armed forces and an estimated 300 armed Muslim rebels in blockaded areas of the city.
"The situation continues to be contained," Roxas said. "Government forces continue to come in and adopt a nonaggressive stance," he said, adding that the government's policy was to show restraint during the siege.
He confirmed that five hostages were released Tuesday in exchange for food and that the death toll had climbed from six to seven after one of the wounded died overnight. He said 36 people had been injured in the siege.
Rebels, he said, had also fired on security forces and government aircraft with mortars and rocket-propelled grenades.
"We continue to condemn these acts," Roxas said.
Brig. Gen. Domingo Tutaan Jr., a military spokesman, said the military was doing everything it could to prevent the violence from spilling over to other parts of the country, PNA reported.
He said government forces and the rebels had a sporadic firefight in the Barangay Santa Catalina area Wednesday afternoon.
Tutaan also said two rebel fighters were killed and one injured after a reported firefight in Barangay Canelar, the news agency reported.
Fire department authorities told reporters that firefighters had been fired on in Santa Barbara, an area in Zamboanga held by the rebels, but there were no reports of injuries.
Zamboanga's mayor, Isabelle Climaco Salazar, said in a Facebook post that a curfew would be in place overnight and that public and private schools would remain closed Thursday.
Only government offices providing front-line services will operate Thursday, she said.
The mayor also urged citizens to report security concerns to authorities rather than posting them on social media "to stop undue panic."
She said incidents involving the MNLF were occurring only in the Talon-Talon, Santa Barbara, Santa Catalina, Kasanyangan, Canela and Mampang areas.
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 a violent campaign.
Under the terms of the 1996 agreement, Misuari was named as governor of an expanded Autonomous Region in Muslim Mindanao, or 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, or 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 Laura Smith-Spark contributed to this report.