The Resistance Committees accused Youssef of refusing to integrate group members into the police force, despite a previous agreement to do so.
In another incident, members of a Hamas militia engaged in a daytime gunbattle with security forces. The gunbattle broke out when Hamas and Fatah loyalists argued over who had control of a nearby training compound in Gaza City, security officials said.
The Fatah-allied security forces demanded that the Hamas militiamen leave the area, but the latter refused, saying it fell under the control of the Hamas-controlled Interior Ministry, security officials said. There were no injuries
Earlier in Gaza, unknown assailants fired shots at the house and car of a senior security officer who has had past problems with Hamas, security officials said.
AP contributed to the report