At least 15 people have been killed and more than 150 injured in what is thought to be an Israeli airstrike in a crowded shopping area.
The Israeli army had no immediate comment on the incident.
Gaza health officials said the area was busy because residents thought a ceasefire was in place.
Israel had earlier announced a "humanitarian window" in certain parts of the territory.
It said it would not halt fire in other areas, including Shijaiyah, where the attack took place.