In Stalingrad after the initial carpet bombings by the Luftflotte 4 under the command of Wolfram Freiherr von Richthofen (cousin of the famous Red Baron) thousands of civilians attempted to cross the Volga river through barges or other means. The NKVD assumed control over the river crossing and prioritized military supplies and evacuation of wounded, by the start of the battle for the city 50 to 100,000 civilians were still trapped inside unable to cross over to the Eastern bank of the Volga and to relative safety. Most of the city at that point had been reduced to rubble and ashes, the suburban wooden homes had burned to the ground under incendiary bombs and left a veritable forest of chimney stacks. Most of the shelter that was created for the unlucky ones still left were in basements, cellars, makeshift houses carved into the banks of rivers and gorges, or shacks made out of debris. The sewer system also served as a refuge for both soldier and civilian alike in the ensuing slaughter. There was little to no food for the civilians that were not drafted into makeshift 'special battalions' made up of non essential workers from the industrial north of the city manning the Barrikady, Red October, and massive Tractor works - that still refit and ran production lines straight into the heart of battle. Many tank crews would drive the unpainted T-34's straight into battle with no gun sights or other equipment. Gunners would have to fire point blank peering down the unloaded barrel.

Those that were drafted into the 'special battalions' were only given a weeks training at best and armed with insufficient arms or ammunition - they would take part in the defense of Spartanovka - a suburb to the north - and other sectors of the city, suffering appallingly high rates of desertion and casualties. The discipline enforced by the NKVD was harsh and unforgiving - militiamen could be tried not for only for desertion or surrender, but even for defeatism or failure to inform comrades of another's escape.

The civilians in the city had no food or clean water, many children would scamper out at night in search of food or water because they presented smaller targets. A favorite place to search for food was the great Grain Elevator to the south which had been a monumental task for the 6th army to clear. Children would attempt to gather smoldering remnants of the grain from the burning elevator now under German control - children would be shot attempting to take food from the elevator, or even soviet positions. There was absolutely no quarter given to those attempting to requisition military supplies for themselves. The German military confiscated and looted anything they could get their hands on from the villages in the region around the city and in the Don bend. Even Cossack villages initially welcoming the Germans as liberators soon scorned them as they took every animal, foodstuff, and blanket from their homes. Civilians robbed of all supplies including winter clothing were simply left to starve and freeze in the oncoming winter. A great number of those trapped in the city, and the eventual Kessel formed by Operation Uranus would not make it to see the end.

Later on in the siege when the Germans ran desperately short of supplies - they would evict citizens from their own small hovels and use the supplies to built bunkers and shelters for themselves - leaving the homeless to gather what little they had onto sleds and try and brave the unbelievably cold winter: with predictable results. At one point due to a shortage of horses the Germans would use starving Soviet POW's as human pack animals to pull heavy guns or carriages loaded with ammunition and supplies: leaving the rest who were too sick in their unsheltered barb wire pens. Those abandoned in the pens or still being held under guard resorted to digging into the frozen ground with their bare hands to provide some semblance of shelter - thousands froze to death in the snow and freezing rain

tl;dr - civilians had very little food, clothing, or shelter - what they did have was often stolen, and foragers were often shot as well. Life was a complete hell and few who lived in it survived to see the end

Source: Stalingrad - The Fateful Siege Anthony Beevor

Often you see massive streams of refugees, plenty of modern day examples unfortunately. People trying to escape the violence, but rarely are they welcome elsewhere of course. It's by no means a new phenomenon, and has existed as long as wars have.