Dr. Marwan al-Hams, director of the field hospitals' department at the Gaza Health Ministry, announced the toll from Tuesday's strike in the northern town of Beit Lahiya at a news conference. He says another 17 people are missing.
The ministry's emergency service says the dead include at least 12 women and 20 children, including babies.
There was no immediate comment from the Israeli military, which has been waging a large-scale operation in northern Gaza for more than three weeks, targeting what it says are pockets of Hamas militants who have regrouped there.
Dr. Hossam Abu Safiya, the director of the nearby Kamal Adwan Hospital, said it was overwhelmed by the wave of wounded people from the strike. Israeli forces raided the medical facility over the weekend, detaining dozens of medics. Israel says it detained scores of Hamas militants in the raid.
The Israeli military has repeatedly struck shelters for displaced people in recent months, saying it carried out precise strikes targeting Palestinian militants and tried to avoid harming civilians. The strikes have often killed women and children.