A crowded neighborhood in central Gaza where many Palestinians fleeing the fighting had taken shelter was mourning a new trauma on Monday after Gaza health officials said an overnight attack had killed dozens of people there.

Photos of the aftermath on Monday showed a gray concrete building gaping with dark holes where rooms used to be. At the foot of the building was a mound of debris, where men appeared to be digging for survivors, or bodies.

The Gaza Health Ministry said 70 people had died in Sunday’s attacks on the neighborhood, Al Maghazi. But the ongoing difficulty of reaching residents in Gaza, where electricity shortages and communications blackouts have frequently obscured the picture of the war’s fallout, meant the details were blurry.

Ministry officials blamed Israeli airstrikes for the deaths. Israel’s military said Monday it was reviewing the episode.