In northern Syria, the crisis is deepening. Millions of people are trapped between advancing Syrian forces, and the Turkish border that is closed to them. The main city in the region, Idlib, swelled to 3 million people as civilians fled the fighting in other parts of Syria and took shelter there. Now, the UN says there is no safe shelter in the city. The BBC’s Quentin Sommerville reports from Idlib Province on the dire circumstances there.