DONETSK, Ukraine (CNN) -

In the city of Donetsk, the devastation wrought by weeks of fighting between pro-Russia rebels and Ukrainian forces is all too apparent.

And as the civilians caught in the crossfire sweep up the debris of their homes and livelihoods, they are hardened against a president they say is killing his own people.

Alexander Omelyavenko, a Donetsk resident, told CNN, "We are Ukrainian but they kill us, so we probably need our own country. Because these people in Kiev, they are not brothers for us."

Another resident, Victoria Khrushova, wiped away tears as she told how her family had been forced to hide from the shelling in cellars.

"We live underground. It was so hard for two weeks -- especially 27th, 28th, 29th -- but only today is quiet," she said.

The husband of a 34-year-old woman killed outside a block of flats last Wednesday wouldn't talk to CNN, saying he was in shock. He made it down to the cellar with their small child but she simply didn't have time. A 50-year-old woman was killed with his wife.

It's a story which repeats itself over and over in dozens of apartment blocks, with civilians being killed by the constant shelling around Donetsk. Windows are shattered, holes blasted in walls and blackened rafters which once supported the roofs of homes stand in bleak outline against the sky.

The victims are the human face of a humanitarian catastrophe unfolding even as diplomatic efforts to curb the fighting plow on.

The United Nations' refugee agency, UNHCR, said Tuesday that the number of people displaced in Ukraine by the fighting, particularly around Donetsk and Luhansk, had more than doubled in less than a month.

While an estimated 117,000 had fled their homes as of August 5, the agency puts the number displaced as of September 1 at 260,000.

UNHCR believes the actual number displaced is higher, as many are staying with families and friends and choose not to register with the authorities. Nearly 95% of those forced from their homes are from eastern Ukraine and most remain in the region, its report said.

'Be human... Stop this war'

Donetsk, once-thriving, is now half-empty, shop fronts shattered and its railway station bombed.

Its trauma hospital is filled with the civilian wounded who were unable to reach safety in time as the shells rained down.

Medical teams treat market traders with shrapnel embedded in their legs or the broken limbs of pensioners too old or sick to run.

"There was one war and this is the second war. I was born in 1940 in World War II and I will probably die before this war is over," said elderly resident Valentina Sergeyevna.

Valentina Popova, in the ward next door, has lost her leg and her arm to indiscriminate artillery shells.

Switching to the Ukrainian language, she made a heartrending plea to Ukrainian President Petro Poroshenko.

"We used to dance, sing, do everything in Ukrainian. Poroshenko, Mr. Poroshenko -- please listen to us. Why don't you understand your people? Be a man. Be human. Please stop your aggression. Stop this war."

Russia accuses the Ukrainian government of precipitating the humanitarian crisis by pursuing its campaign to regain territory seized by the rebels.

Meanwhile, Poroshenko and some Western allies have said thousands of Russian troops are in his nation's east, helping the separatists.

NATO members meeting this week in Wales are expected to create "a very high-readiness force" to deal with Russian aggression in Ukraine and other international conflicts, NATO Secretary General Anders Fogh Rasmussen said Monday.

European Union leaders are expected to decide on further sanctions against Russia over its actions in Ukraine by Friday, Italian Foreign Minister Federica Mogherini said Tuesday.

Lavrov: 'Let us sit down and talk'

Though Russia has denied sending its troops to Ukraine, it has defended the rebels' action in the east.