In a flash, a view of Ukrainian civilians fleeing down a street in Irpin becomes only concrete dust.

The scene captured in a video Sunday shows a mortar shell falling in the street, killing three family members and a family friend — including two children.

This is the kind of danger looming over the people of Ukraine. Some have decided to leave their homes and loved ones behind to risk an escape. Others who must stay are helping to ready a resistance to the overwhelming Russian military power.

CBC senior correspondent Susan Ormiston is in the city of Lviv in Western Ukraine, where she’s been talking to Ukrainians, both those who are fleeing and those getting ready to fight. Today, she brings us to a train station, a border crossing, a bomb shelter and a barricade, and explains how Ukrainians have made these impossible choices — if they had any choice at all.