Syrian government troops completely encircled rebel-held neighborhoods last week, cutting off all supply lines to the enclave.
Fierce fighting has ensued as rebel militias have attempted to break the siege, and regime troops, backed by Russian air power, have responded with intense strikes on opposition-controlled areas.
Three barrel bombs were dropped on eastern Aleppo as photojournalist Karam Al Masri spoke to CNN from his home in the Bustan al-Qasr neighborhood Wednesday evening.
He said the airstrikes began at around 7 a.m. and continued through the day -- about 10 missile strikes, and about 20 aircraft dropping feared barrel bombs.
"Each aircraft carries two barrel bombs. At times two or three aircraft drop them at the same time," he told CNN.
"They are the most dangerous. They cause a lot of damage and people are most scared of them. When it's bad like that, everyone goes to the bottom floors."
At least 16 people, including four children, were killed in the past 24 hours by heavy aerial bombing in Aleppo province, the UK-based Syrian Observatory for Human Rights said Thursday.
Ten of those were in rebel-held neighborhoods in eastern Aleppo, voluntary rescue group Syria Civil Defense said, with fatalities expected to rise due to the lack of medical equipment.
Man killed, child wounded
Masri said he took cover in a basement for an hour with about 15 neighbors as strikes hammered the area Wednesday.
Masri said he witnessed one man in the neighborhood die. Seven others were injured.
"One of them was a child who lost his leg, and he is now in a serious condition. He was just 7 or 8 years old," he said.
He said he believed the airstrikes intensified Wednesday after residents ran out of tires to burn and create thick smoke clouds to obscure targets from bomber pilots.
Children have joined efforts to burn the tires in defense of their neighborhoods as airplanes circle overhead.
Concerted rebel push
Intense battles -- some of the fiercest in the five-year conflict to date -- have broken out this week as rebels attempt to drive through government lines and reconnect with opposition-held territory in the west.
Hospitals supported by Doctors Without Borders in rebel-held Aleppo have seen a significant increase in wounded since the fighting intensified, said Pablo Marco Blanco, Middle East operations manager for the humanitarian group.
On Wednesday, rebels detonated a huge bomb in a tunnel beneath a government position in the strategic Ramouseh area, a regime-held neighborhood separating eastern Aleppo from the rebel-held territory to the west.
Rebel militia initiated attacks on other government-controlled areas, the Syrian Observatory for Human Rights said.
Goods scarce, prices skyrocketing
About 250,000 people are facing a humanitarian crisis in eastern Aleppo since the government cut supply lines to rebel-held areas, the United Nations says, with severe medical shortages and food stocks tipped to run out within weeks.
In the once-bustling markets of Aleppo -- pre-war Syria's economic hub -- basic goods are hard to come by, Masri said.
Most markets and shops were closed anyway Wednesday due to airstrikes, he said.
"The prices for goods are skyrocketing," he said, adding that the cost of a liter of gasoline had increased sixfold, "that is if you can find it." The price of tomatoes has risen by four times, residents say.
"People are slightly hopeful that the battles on the west side will end up helping lift the siege, so they can regain access to food and medicine," he said.
Resident: 'These are imaginary corridors'
Russia and Syria say they have opened humanitarian corridors into eastern Aleppo to allow for the distribution of aid and to give residents -- along with rebels who choose to surrender -- a chance to leave.
They say that both civilians, and rebel fighters who have laid down arms, have used these routes -- although the figures they give are a fraction of those believed to be in besieged Aleppo.
Residents of eastern Aleppo and international observers say the corridors do not appear to be in wide use, with people skeptical of government assurances for their safety.
Abu Nizar Firas, a resident of eastern Aleppo, said the corridors were not safe, and it was impossible for young men to leave.
"These are imaginary corridors, false corridors only to show the international community that they are working on humanitarian issues with the Russian side," he said.
"Everyone who went there found out that they are very dangerous for crossing."
Another resident, Salem Ahmed, said no humanitarian corridors had been opened -- but he would not leave even if they were.
"I would never leave -- it's my land, my town and my country," he said.
"True, there are ongoing bombings, but at least we are in our lands."
Jan Egeland, humanitarian adviser to the U.N. envoy to Syria, told CNN he thought few people were leaving via the corridors. The United Nations has called for an international humanitarian operation to relieve areas under attack, involving a 48-hour break in fighting agreed to by all parties.