Israeli airstrikes in Gaza City and the Bureij refugee camp killed more than 40 people, including 19 women and children, according to health officials.
In Gaza City, 14 people died when a strike hit a residential block, including a hospital nurse and his wife and three children.
Another strike at Bureij refugee camp killed at least eight Palestinians, including four children and two women, and injured 22 others.
Most of the victims were taken to Shifa and Al-Awda hospitals, the Associated Press has reported.
Israel has not commented on the strikes, which come as several European countries and key U.S. allies move to recognize a Palestinian state.
