"No doubt we are failing the people of Mariupol," U.N. relief official says

As Russian forces continue to besiege the Ukrainian port city of Mariupol, the head of U.N. emergency relief efforts offered a grim assessment of the situation on the ground: "No doubt we are failing the people of Mariupol," Martin Griffiths, Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator said Monday.

"It's a place I've described as a center of hell," he said. 

He said the U.N. receives offers "day by day" to create humanitarian corridors that are "not cleared by" one side or the other, and families have been trapped.