Thousands of residents were heading out of Donetsk in eastern Ukraine on Saturday, fearing more violence as government forces moved closer to the city.
Families queued for hours to get on a train that would take them to a safer part of the country.
Separatist leaders estimate 70,000 residents have already left the city.
One woman said: “We’re going to Crimea. We’ll return if the Donetsk People’s Republic holds out and if the monstrous Ukrainians come, then there will be no return. How can you live with them if they’re killing people.”
Rebel fighters have been holding out against government forces although the the airport is still controlled by Ukrainian forces.
The Ukrainian military say they have a plan to deliver a “nasty surprise” to the rebels.
President Poroshenko also promised a crackdown saying: “for every soldier’s life, the militants will pay with scores and hundreds of their own. Not a single terrorist will avoid responsibility; each will get what they deserve.”
On Friday the Ukrainian army suffered heavy losses when a missile attack by rebels killed 23 servicemen and wounded nearly 100.