A "humanitarian pause" began Thursday in the Syrian army's Russian-backed assault on rebel-held areas of Aleppo but clashes continued and there were no signs residents were heeding calls to leave.
The unilateral ceasefire took effect at 8:00 am 0500 GMT) and was to last at least 11 hours, with the aim of allowing civilians and fighters to evacuate the city's opposition-controlled east.
Gunfire and artillery exchanges erupted around a crossing point near the rebel-controlled Bustan al-Qasr district shortly after the pause began, an AFP correspondent said.
State news agency SANA said "terrorist groups" had targeted the area around the corridor with rocket, machinegun and sniper fire "in an attempt to hinder the humanitarian pause".
Russia has said the pause will continue until at least 1600 GMT and could be extended.
The Syrian army has said it will last three days and on Thursday soldiers were calling through loudspeakers for residents to "seize the chance" to evacuate.
Russia announced the ceasefire earlier this week to allow civilians and rebels to quit the east of Aleppo, the divided northern city that has been devastated by Syria's five-year civil war.
Moscow is backing President Bashar al-Assad's regime in the conflict and has faced increasing international pressure over the destruction and civilian deaths caused by Russian and Syrian air strikes.
Russia has described the pause as a "goodwill gesture" but rebel groups have said they will not abandon their posts and, with Aleppo encircled by pro-government forces, many civilians fear falling into the hands of the regime.
Western powers have also expressed scepticism. European Union leaders gathered for a summit in Brussels on Thursday were to strongly condemn Syria and Russia over Aleppo and were weighing sanctions.
More than 250,000 civilians have been trapped in the rebel-held east of the city under near-continuous siege since mid-July.
The Syrian army has said it is opening eight corridors for civilians to leave, two of which can also be used by rebel fighters provided they leave behind their weapons.
The Russian defence ministry was streaming live video from several of the corridors, showing waiting ambulances and buses along empty roads.
Yasser Youssef of the Nureddine al-Zinki rebel group said opposition fighters wanted "nothing to do" with the Russian initiative.
"Who are they to decide to displace the Syrian people who rebelled against the dictator Assad?" he asked. "We will not abandon our right to defend our people and ourselves."
Some civilians interviewed by AFP said they were eager to leave but wanted more reassurance they would be safe.
"I don't want to risk my life or my family's by being among the first to leave," said Mohammed Shayah, an unemployed father of four.
The United Nations has said the duration of the pause is not enough to provide any relief supplies.
UN envoy Staffan de Mistura said the truce would be long enough to safely evacuate just 200 wounded.
More than 2,000 people have been wounded since the army launched a new offensive last month aiming to take the entire city, according to the United Nations. Some 400 have been killed.
The civilian casualty toll has drawn international condemnation, with Washington saying the bombardment could amount to a war crime.
Moscow has dismissed the accusation as propaganda that ignores the reality of the presence of jihadist fighters blacklisted by the United Nations in rebel areas.
It has repeatedly demanded that fighters of other rebel groups break ranks with the former AlQaeda affiliate, the Fateh al-Sham Front.
Russian President Vladimir Putin held tough talks with the French and German leaders in Berlin on the eve of Thursday's EU summit.
Francois Hollande condemned the bombing of Aleppo as "a war crime," while Angela Merkel described it as "inhumane and cruel".
According to a draft summit statement obtained by AFP, EU leaders were weighing sanctions against supporters of Assad's regime if they fail to stop atrocities.
"The EU is considering all options, including further restrictive measures targeting individuals and entities supporting the regime, should the current atrocities continue," according to the draft.
Though Russia is not mentioned explicitly regarding sanctions, the draft singles out Moscow for its actions in Aleppo.
"The European Council strongly condemns the attacks by the Syrian regime and its allies, notably Russia, on civilians in Aleppo," it reads.