Hamas executed 18 people on Friday, some of them in the streets of Gaza City in the middle of the day, after accusing them of collaborating with Israel, according to media linked to the Islamist group, which rules the Gaza Strip.

The killings followed what appeared to be a burst of improved Israeli intelligence-gathering that facilitated airstrikes against Hamas commanders this week.

In one instance, about 20 militants dressed in black and with their faces covered brought six of the condemned men, their heads covered with cloth bags, to an alley near the Great Omari Mosque in Gaza City after midday prayers, witnesses said. A militant shot the men in the head one at a time with a pistol, after which he sprayed them with automatic rifle fire, the witnesses said. The bodies were loaded into government ambulances and taken away.

A total of 11 accused collaborators were executed in Gaza City on Friday morning, and another seven were executed around noon, the Hamas-affiliated news service Safa said. Three other executions were carried out Thursday, the news service said.

While Palestinian militants have executed suspected collaborators in past conflicts with Israel, the number of executions over the two days was unprecedented, according to Bahjat Hilu, the Gaza-based spokesman for the Independent Commission for Human Rights, a Palestinian rights group.