Vova doesn't know there is a right outside his window.

He doesn't understand the meaning of the air raid sirens. He is unaware of the destruction caused by Russian . He just wants to build towers from his toy blocks and press the buttons on his mom's phone that make it play songs and cartoons he likes.

Vova, a pet name for Volodymyr, is 17 and has Opitz-Kaveggia syndrome, a rare genetic condition that causes severe intellectual disabilities. He needs round-the-clock care and anti-seizure medication that has become impossible to obtain as Russian troops close in on the Ukrainian capital, according to his mother, Natalia Komarenko.

"We are unable to get the medicines we desperately need -- anticonvulsant drugs Levetiracetam and Lamotrigine. He has been taking them since he was 10," she told CNN.

Evacuation is not an option for the Komarenkos because Vova's condition makes travel extremely risky.

"We can't take him by train, because at any moment he may have a seizure and his temperature may rise. He may not always voice his need to go to the bathroom, and he can't be left unattended even for a minute," Komarenko said, adding that driving is also dangerous, in case he has a seizure.

"We can't even run downstairs to the bomb shelters. We mostly hide in the corridor of our apartment, in the bathroom or the toilet," she said.

Vova and his family are among thousands of Kyiv families that cannot leave the city because of health conditions.

Komarenko heads a charitable foundation called (Ukrainian for "With Warmth in the Heart"). The group brings together and creates support networks for Kyiv families living with disabilities. Only 20 to 50 of the 1,247 families in the group — around 260 people in all -- have been able to flee the capital, according to Komarenko.

The European Disability Forum, a pan-European NGO, estimates there are 2.7 million people with disabilities in Ukraine. According to Inclusion Europe, another NGO, there are around 261,000 people in Ukraine with intellectual disabilities that make them extremely vulnerable to the conflict.

At least 100,000 of them, mostly children, live in care homes and institutions. Their chances of getting out of the country are slim.

The journey out is long and hard, even for families not facing the additional challenge of disability. For those dealing with serious health conditions, it is nearly impossible.

Daryna Chuiska has been stuck near the Polish border with her daughter Vika for several days. Vika, 10, has cerebral palsy and asthma and desperately needs to resume her physical therapy.

"Vika has been without rehabilitation for a very long time, her condition is deteriorating," Chuiska said. "She is constantly growing and her muscles do not develop at the same pace, so she is starting to lose the progress. She has started falling while walking and her legs are not developing well, she has pain in her legs now."

The journey from their hometown in central Ukraine to the border took days and has been exhausting for Vika. Her condition has deteriorated. The pair spent several days hiding in basements, where Vika developed a dry cough and shortness of breath. They were sleeping in their clothes, listening to the thunder of planes overhead.

"At night Vika started having seizures. Last time she had seizures she was five years old, she hasn't suffered from seizures since then," Chuiska said. She believes Vika's seizures were brought on by the stress of the journey and the damp conditions in some of the basements in which they stayed.

Chuiska told CNN she has secured a place for Vika with a host family in Germany who have arranged the crucial therapy for her. But they need to get there on their own.

So far, Chuiska hasn't been able to find transportation. Vika is severely allergic to cats, which makes it impossible for the two of them to follow the hundreds of thousands of Ukrainians who took the train to Poland.

"The trains and buses are full of pets, so it is too dangerous for her," Chuiska said. At one point, she and Vika were very close to getting across the border, having secured a car to take them there.

"But the person stopped picking up the phone. There's another option to get to the border and then walk for three kilometers, but Vika can't walk that long," she said. Someone else also offered a lift -- but only if she transferred money first. Chuiska, worrying it was a scam, refused. For now, they remain near the border, looking for a safe way out.

'WE HAVE TO SURVIVE'

Olena Tsarenko, who is also involved in the group, is one of those who made it out. She fled with her two daughters, her mother and Amour, the family dog.

Tsarenko and other families with disabled children traveled from Kyiv to Warsaw after the invasion started on February 24. The train journey took two days, then they traveled further by bus.

Tsarenko's 10-year old daughter Veronika has autism and doesn't speak. The only thing she can say is "mom." To Tsarenko's surprise, Veronika remained relatively calm throughout the journey.

"It was a very hard and exhausting trip and I don't know what happened, but Veronika wasn't crying. But now all night long, she's crying and she's in distress," she said.

Tsarenko said the decision was incredibly hard, and she still feels guilty about it.

"I feel like I should have stayed in Kyiv and worked, but I am also the only person who can take care of my family, so my mom instinct says please, Olena, you must save Mary and Vera. But I feel guilty ... all my friends are there. The people who stay in Ukraine are heroes," she said. Since getting to Warsaw, she has spent her time volunteering, making sandwiches for fellow refugees stuck at the border and helping arrange help for other families from the Z teplom u sertsi group.

Veronika is now getting the medical attention and the rest she needs. She can't express her feelings, but Tsarenko believes her daughter understands what is happening to her home country.

"Every day she's listening to this song called 'We have to survive.' She is playing it on YouTube and from morning until the evening she is listening, and listening again and again on the phone. And I allow her to listen to this song because it calms her down," she said.