Intensifying conflict in the south of Gaza has trapped a team of international doctors, including Americans, in a hospital near the city of Rafah, further jeopardizing conditions for both the aid workers and scores of their critically wounded Palestinian patients, medical personnel told The Washington Post.

The medical workers were due to leave Gaza Monday after a two-week rotation in the European Hospital in Khan Younis, an area near Rafah. Doctors there said they are no longer certain when they can leave, or if they can safely reach the border with Egypt. The Rafah border crossing relied upon by aid organizations remains under Israeli control, and on Monday morning, a United Nations staff member traveling to the European Hospital was killed when their vehicle, which was marked with a U.N. flag, was attacked.