(CNN) -- Syrian troops killed at least 20 civilians and rounded up more suspected anti-government protesters Thursday, a day after the government pledged to end the months-long clampdown, opposition groups said.
Syrian aircraft buzzed the besieged neighborhood of Baba Amer in the northwestern city of Homs, where witnesses reported fighting between government troops and deserters who had sided with opposition groups. The Local Coordination Committees of Syria, an opposition group, said 19 people were killed in Homs and three others in Idlib, near the Turkish border, while the London-based Syrian Observatory for Human Rights put the death toll at 20 in Homs.
Gunfire could still be heard in some neighborhoods in Homs around nightfall, the Syrian Observatory reported. The Local Coordination Committees also reported arrests of student demonstrators in Aleppo, Daraa and Damascus, where it said several homes had been raided by security forces.
Meanwhile, Syria's official news agency SANA reported that 13 soldiers and police officers had been killed fighting "armed terrorist groups" in Hama, Homs and Idlib. CNN cannot independently verify the reports from either side, since Syria's government has limited access to international news organizations.
The latest developments reports come a day after the government of embattled President Bashar al-Assad agreed to an Arab League plan to bring an end to the crisis in Syria. The government agreed to pull its army off the streets, release people jailed since the protests began in March and allow international journalists and Arab League observers to monitor the moves, Arab League ministers announced Wednesday.
The regional organization will moderate a "national dialogue" after two weeks, the ministers said.
Syria has made previous pledges to withdraw armed forces from civilian areas. But in some of those cases, it withdrew only armored units and left infantry in place, or returned after a brief pullout. Anti-government activists criticized those steps as efforts by al-Assad's regime to buy time. It also has made other moves aimed at defusing the protests, including plans to draft a new constitution, but they have failed to appease the demonstrators.
The Free Syrian Army -- a group of military deserters who have helped defend anti-government protesters -- said it would abide by the Arab League agreement "as long as the regime commits to the same." But it warned that if the government fails to abide by the deal, "We will be compelled to protect the protesters and work on bringing down the regime no matter how much that may cost us."
The United Nations estimates that more than 3,000 people have died in Syria since anti-government protests erupted in March, amid the Arab Spring movements that have rocked the Middle East and North Africa. Al-Assad and other Syrian officials have blamed the violence on outside forces attempting to undermine the 40-year rule of the president's family.
SANA reported the Arab League agreement Thursday, with Arab League Ambassador Yousef Ahmad quoted as promising Syria would carry out reforms and draft a new constitution "in spite of the vicious campaign against it."
"Ambassador Ahmad expressed hope that the document will be the beginning of an ongoing, honest and transparent cooperation based on true commitment to Syria's security, stability and unity and the prosperity of its people," SANA said.
Ahmad also said Syria "will remain under the leadership of President Bashar al-Assad a haven for all Syrians and Arabs," according to SANA.
A Syrian opposition figure, Samir Nashar, met with Arab League Secretary-General Nabil Al Araby on Thursday at the League's headquarters in Cairo, a source within the organization told CNN. Nashar is the head of the Syrian National Council, a recently formed opposition group supported by a coalition of Egyptian activists.
Opposition figures are still demanding al-Assad's ouster and refuse any dialogue with the president, but the Arab League source said they may consider negotiations toward the transfer of power to a democratic government.
"The opposition demands al-Assad to step down and accuses him of stalling," the source said.
CNN's Arwa Damon and Hamdi Alkhshali and journalist Mohamed Fadel Fahmy in Cairo contributed to this report.