Syrian regime carries out attacks in Aleppo despite Russian cease-fire effort

ALEPPO, Syria, Aug. 11 (UPI) -- Fighting is occurring in Syria's besieged city of Aleppo on Thursday despite a Russian promise to stop military action to allow for humanitarian aid, emergency officials said.

The Syrian Civil Defense volunteer rescue group said at least four people died in a toxic gas attack -- believed to be chlorine gas dropped from a barrel bomb -- on a rebel-held area of Aleppo. Russia's military previously announced a daily three-hour suspension of attacks.

Though it is unclear if Russia's military participated in Thursday's attacks amid a proposed three-hour cease-fire, the Syrian regime did not participate in the halt to hostilities, according to local sources, BBC News reported.

Local groups said warplanes belonging to the regime of Syrian President Bashar al-Assad conducted airstrikes on the district of Hreitan in the northern outskirts of Aleppo. Helicopters and warplanes took part in fighting between government forces and rebels in Aleppo's Hamdania and Ramouseh districts.

The United Nations said Russia's proposed daily halt to hostilities between 10 a.m. and 1 p.m local time is not enough to help the large number of people within the city who need aid.

"We have supplies ready to roll -- food rations, hospital supplies, ambulances, fuel for generators, water supplies and more," U.N. Emergency Relief Coordinator Stephen O'Brien said in a statement. "We will continue to use all available routes and mechanisms to do this, including cross-line and cross-border operations from Turkey. We can deliver these within 24-48 hours -- if we have safe access."

Russian warplanes on Thursday also targeted the Islamic State in the northern city of Raqqa, considered the militant Islamist group's stronghold.

Fifteen doctors -- out of a remaining 35 -- in rebel-held eastern Aleppo penned a letter to U.S. President Barack Obama urging him to intervene in the bombardment of hospitals by Assad's air force.

"We do not need tears or sympathy or even prayers: We desperately need a zone free from bombing over eastern Aleppo to stop the attacks, and international action to ensure Aleppo is never besieged again," the doctors wrote.