Aleppo, Syria (CNN) -- Two dozen U.N. monitors fled Aleppo on Tuesday, joining the steady stream of civilians who are escaping the fighting between rebels and regime forces.
"We have pulled out the entire team of observers from Aleppo today due to the deteriorating security situation there in the city," said Juliette Touma, a spokeswoman for the U.N. Supervision Mission in Syria.
"This is a temporary move back to Damascus and we still hope to return the team when the security situation allows."
People who aren't able to flee the city hunkered down in their homes or shelters. They fear a bloodbath as the Syrian army masses its forces on the outskirts of the city.
The Free Syrian Army remains ensconced in many Aleppo neighborhoods, but it has endured a pounding from Syrian forces for days and days.
Blasts rattle the city through the night, and the Levantine metropolis is coming to resemble a battered urban moonscape.
Several Aleppo neighborhoods took artillery fire Tuesday morning, striking panic among residents.
Opposition forces report warplane strikes on the Bab al-Hadid and Bab Al-Nasr areas, and shelling is raging in the Salaheddine neighborhood.
All, especially children, are traumatized.
At one bakery, about 100 men, women and children lined up, waiting 90 minutes for bread. Most of them lack cooking gas and have to cook their food over firewood.
Some people have moved to rebel-controlled areas regarded as safer. Others have moved to the countryside, escaped to Turkey or taken refuge in government-controlled neighborhoods.
One man said he left the city recently and then returned, hoping things would be calmer. But he saw people in the rebel-controlled parts of Aleppo packing up and leaving.
There's desperation among rebel fighters too, as they wait for more munitions to arrive.
One field hospital was overwhelmed by rebel fighters wounded in attacks by Syria's air force. Doctors lacked enough staff, medicine and supplies to deal with the wounded.
With their hands covered with the blood of the fighters they were treating, they made cell phone calls to doctors and nurses in other neighborhoods for urgent help.
Amnesty International, meanwhile, released a series of satellite images from the Aleppo area, including one that shows "more than 600 probable artillery impact craters" in the nearby town of Anadan.
"Turning Syria's most populous city into a battlefield will have devastating consequences for civilians. The atrocities in Syria are mounting already," said Christoph Koettl, emergency response manager for Amnesty International USA.
"The Syrian military and the opposition fighters must both adhere to international humanitarian law, which strictly forbids the use of tactics and weapons that fail to distinguish between military and civilian targets."
CNN's Brian Walker and Joe Sterling contributed to this report.