The United Nations is warning that Syria’s government has dramatically stepped up bombing and shelling attacks on civilian areas of Idlib and Hama. This is U.N. humanitarian chief Mark Lowcock, speaking to reporters Tuesday after pleading with the U.N. Security Council to help stop the violence.

Mark Lowcock: “There’s been a bloody onslaught, in full swing now for more than three months, on the people of Idlib. And if it doesn’t stop, as I’ve said before, it has the potential to create the worst humanitarian disaster the world has seen so far this century.”

Activists say recent attacks in Idlib appear to be deliberately aimed at health facilities. A medical worker in the region told Doctors Without Borders, “Patients, their caretakers and hospital staff are all struggling psychologically. When planes fly over the hospital, they are extremely scared—some leave the building out of fear it will be hit.” Over the past three months, the assault has forced more than 450,000 people to flee north toward Turkey.