Hamas killed at least 18 Palestinians, including two women, Friday that it suspected of collaborating with Israel, the Jerusalem Post reports. That number is expected to grow.

Eleven suspected collaborators were murdered at a Gaza police station and then Hamas terrorists proceeded to kill seven more Palestinians in a public execution, according to witnesses and an official Hamas website. The victims were shot in front of a crowd of worshipers outside a mosque after prayers.

A Palestinian Facebook page showed a picture of people outside the Gaza City waiting for more public executions. Amnesty International issued a statement calling on Hamas to stop the killings, which Director of Research and Crisis Response Anne Fitzgerald described as "even more shocking by the fact that the victims were sentenced to death after trials which, if they happened at all, were summary and grossly unfair."

This escalation in arrests and quick executions comes in the wake of Israel's targeted assassination of three senior Hamas commanders. Israel's successful intelligence infiltration that enabled the targeted killings has spread fear and mistrust among Hamas' ruling circle. Israel also is preparing for an increase in retaliatory terrorist attacks.

Hamas rockets injured three people in an Ashdod synagogue Friday, and killed a 4-year-old boy in Sha'ar Hanegev.

Hamas also arrested over 150 of its members who will be interrogated over "security leaks," the Post's Khaled Abu Toameh reported on Twitter, citing Arabic news site Albawaba.

Hamas has executed many other Palestinians during the Gaza conflict and arrested a number of women, on suspicion of working with Israel.