Russia is facing a rapidly escalating international outcry as more horrific images and stories are emerging of alleged atrocities being committed against Ukrainian civilians.

One Ukrainian lawmaker said that Russian troops beheaded an elderly woman who was trying to flee the city of Bucha, where bodies have been found in mass graves. 

Ukrainian parliament member Oleksiy Goncharenko said Russian troops beheaded an elderly woman who was trying to flee the city of Bucha, where bodies have been found in mass graves, describing the graphic scene in the Kyiv region as a "scene from a horror movie." 

"That's a real genocide. Russians should pay for these war crimes," Goncharenko said Monday outside the vehicle where the grandmother allegedly was traveling in with her daughter and granddaughter before her gruesome death, according to Reuters.

WARNING: GRAPHIC IMAGES BELOW

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Ukrainian officials say the bodies of 410 civilians were found in Kyiv-area towns and cities – like Bucha – that were recently retaken from Russian forces. 

Associated Press journalists saw the bodies of at least 21 people in various spots around Bucha, northwest of the capital. One group of nine, all in civilian clothes, were scattered around a site that residents said Russian troops used as a base. They appeared to have been killed at close range. At least two had their hands tied behind their backs, one was shot in the head, and another's legs were bound. 

One resident, who refused to give his name out of fear for his safety, told the AP that Russian troops went building to building and took people out of the basements where they were hiding, checking their phones for any evidence of anti-Russian activity before taking them away or shooting them. 

Hanna Herega, another resident, said Russian troops started shooting at a neighbor who had gone out to gather wood for heating. 

"They hit him a bit above the heel, crushing the bone, and he fell down," Herega said. "Then they shot off his left leg completely, with the boot. Then they shot him all over." 

GRAPHIC IMAGE WARNING: Bodies lie in a mass grave in Bucha, on the outskirts of Kyiv, Ukraine, on Sunday.

GRAPHIC IMAGE WARNING: Bodies lie in a mass grave in Bucha, on the outskirts of Kyiv, Ukraine, on Sunday. (AP/Rodrigo Abd)

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Russian troops had rolled into Bucha in the early days of the invasion and stayed up until March 30. 

Russia is denying anything to do with the widespread killing of Ukrainian civilians, with Kremlin spokesman Dmitry Peskov saying Monday that "we categorically reject the accusations." 

Russia's Defense Ministry claimed in a statement that fresh photos and videos of the dead bodies "have been stage managed by the Kyiv regime for the Western media." 

Russia is also asking Monday for a meeting of the U.N. Security Council to discuss events in the city, but the U.S. and Britain have recently accused Russia of using Security Council meetings to spread disinformation. 

GRAPHIC IMAGE WARNING: A body with hands bound by white cloth, who according to residents was shot by Russian soldiers, lies in the street in Bucha, Ukraine, on Sunday.

GRAPHIC IMAGE WARNING: A body with hands bound by white cloth, who according to residents was shot by Russian soldiers, lies in the street in Bucha, Ukraine, on Sunday. (Reuters)

Meanwhile, Russia is facing a growing avalanche of criticism for its military’s actions in Ukraine during an invasion that has now lasted 40 days. 

"You can't help but see these images as a punch to the gut," U.S. Secretary of State Antony Blinken told CNN on Sunday when reacting to photos out of Bucha.  

Blinken said the U.S. is documenting any potential war crimes and vowed "accountability." 

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Spanish Prime Minister Pedro Sánchez said Monday that he hopes "everything possible can be done so that those behind these war crimes don’t go unpunished, and that they can appear before the courts, in this case the International Criminal Court, to answer these alleged cases of crimes against humanity, war crimes and, why not say it, of genocide, too." 

European Union foreign policy chief Josep Borrell said "the Russian authorities are responsible for these atrocities, committed while they had effective control of the area," while U.N. High Commissioner for Human Rights Michelle Bachelet said "reports emerging from [Bucha] and other areas raise serious and disturbing questions about possible war crimes, grave breaches of international humanitarian law and serious violations of international human rights law." 

The Associated Press contributed to this report.