Finding a safe route out of Ukraine is not easy.
One challenge facing those looking to escape is to find one that is not under heavy bombardment from Russian forces.
The UN says more than three million people have have now fled Ukraine since Russia launched its invasion just over three weeks ago.
So how do people actually find safe passage out of the country?
One way is via transport arranged by dozens of volunteers based thousands of miles away, who liaise with fellow volunteers in Ukraine.
They, in turn, send information in real-time about safe roads to drivers who can rescue busloads of people.
But even using this method, travelling is not without considerable danger.
In other words, they are crowdsourcing safe passage out of a war zone.
Civilians evacuating civilians
Artur Kiulian, a Ukrainian software developer living in the US, was one of many who answered the call for assistance from the country's digital minister, Mykhailo Fedorov.
Artur used his skills gained in the tech industry to form UkraineNow, which uses volunteers and messaging apps to evacuate people from Ukraine.
"I've been building tech start-ups for the last decade," he said. "I'm an engineer myself, I have a degree in systems of artificial intelligence.
"There is limited capacity [from] the UN and the Red Cross. There is no-one else to help. It's all civilians evacuating civilians."
When he spoke to the BBC, Artur was organising the evacuation of children with cancer from Ukraine to Poland. From there, they planned to travel to a hospital in Germany.
He and his team organised the bus, the driver, and the place for them to stay across the border.
But crucially, they crowdsourced the safe route too.
How does it work?
Firstly, civilians in Ukraine make requests for help online.
The team in the US receives the requests and allocates them to buses which have been purchased or rented with the money UkraineNow raises.
Drivers are then put in contact with the civilians, and the evacuation is arranged.
The exact process and methods used are more detailed than this, but the information is not being shared here in order to protect the organisation from cyber and real-world attacks.
The BBC spoke to one of the people helping on the ground.
Salam, a former refugee himself, organised a bus filled with people out of a city being shelled by the Russian army and across the border into Moldova.
"We have a [group] of women and children that is going to travel to a safe place," he said. "And then they can travel from there to wherever they want."
He says he thinks he has made the journey from Ukraine to Moldova about 16 or 17 times already in the war.
"It's a dangerous journey," he said. "Everybody's nervous… anything can happen.
"The road is completely empty right now. We're just driving ourselves and we're far away from the border - so we are in no man's land here.
"If they stay in their city they will be bombed. They're running for their lives.
"We have an amazing team doing everything they can. There's so many good people on our team that are trying to help so many people."
'This is destroying families'
Salam explained the desperate situation for the people on his bus.
"There's a lot of sadness here," he said. "A lot of women and children have left their husbands and their fathers, and they don't know if they're going to see each other again.
"They just said goodbye, cried, and they left them. You cannot imagine how difficult it is for them."
One of the people who managed to get aboard Salam's bus is Maryia - not her real name - who says she found out about the escape plan through a messaging app.
"I took this phone number from some group [on the app]," she said. "I don't remember exactly."
She said it was recommended to her by other people in her city, which has been shelled by Russia.
For Maryia, she felt she had no choice but to leave.
"We are going to be without food," she said. "We are going to be bombed in our building.
"I had some work projects, and now they're frozen, and I cannot work. Of course, I cannot get money. So I need to think about my future life.
"I need to survive."
These are the stakes for the evacuees - who in this case were able to escape.
War in Ukraine: More coverage
War in Ukraine: More coverage
Salam was able to guide the bus to the Moldovan border and safety. But there is no guarantee that future journeys will be equally successful.
This is because the margins for the evacuation are incredibly tight. A previous route used to evacuate civilians was devastated by bombings only 10 hours after the bus left Ukraine.
But Salam will continue driving regardless. "We're not going to stop before this war's going to stop, and people can go back to their homes and be safe," he said.
"Until that, we need to show our solidarity and do everything we can to save people."