Hamas police have broken up a protest against a decision to close down Gaza's largest independent youth organization.
Demonstrators say they were beaten and detained while trying to protest in front of the office of Sharek, a UN-funded group that provides youth services. Sharek was shut down by Hamas last week.
They say 12 protesters were arrested, and an Al-Jazeera TV crew was detained for about an hour.
The Hamas attorney general said he has opened a criminal investigation into Sharek.
Hamas police say the demonstration was illegal, and that an Al-Jazeera correspondent was suspected of supporting the group. Al-Jazeera declined comment.