Outside the Zadna Bakery in central Gaza one recent afternoon, the long lines of people waiting for bread were threatening to dissolve into chaos at any minute.

A security guard shouted at the crowds that pushed toward the bakery door to wait their turn. But no one was listening.

Just a few steps away, scalpers were hawking loaves they had gotten earlier that day for three times the original price. The sunset meal that breaks Muslims’ daylong fast during the holy month of Ramadan was approaching and across Gaza, bread, water, cooking gas and other basics were hard to come by — once again.

Lines had not been this desperate, nor markets this empty, since before the Israel-Hamas cease-fire took hold on Jan. 19. The truce had allowed aid to surge into Gaza for the first time after 15 months of conflict during which residents received only a trickle of supplies.