Hamas militants surround Palestinians suspected of collaborating with Israel, before their execution in Gaza City August 22, 2014. REUTERS/Stringer

GAZA (Reuters) - Hamas militants killed seven Palestinians suspected of collaborating with Israel in a public execution in a central Gaza square on Friday, witnesses and a Hamas website said.

The victims, their heads covered and hands tied, were shot dead by masked gunmen dressed in black in front of a crowd of worshippers outside a mosque after prayers, witnesses and al-Majd, a pro-Hamas website, said.

Another 11 people suspected of collaborating with Israel were killed by gunmen at an abandoned police station in Gaza earlier on Friday, Hamas security officials said.

(Reporting by Nidal al-Mughrabi; editing by Luke Baker)