An Israeli airstrike early Sunday killed at least 18 people and wounded many others in central Gaza, Palestinian medical officials said.
The strike hit a mosque sheltering displaced people near the al-Aqsa Martyrs hospital in the town of Deir al-Balah, the hospital said in a statement.
The strikes come as the war in Gaza approaches its first anniversary.
The Israeli military said it was conducting "precise strikes on Hamas terrorists" operating within command and control centers in the mosque as well as a school.
Israeli forces have invaded several hospitals in Gaza over the almost one-year old war, accusing Hamas of using them for military purposes, allegations denied by Palestinian health officials.
Germany, the European Union, the US and others classify Hamas as a terrorist organization.