The Israeli military killed nearly a dozen people Sunday in its latest bombing of a school-turned-shelter in the Gaza Strip, an attack that came amid limited pauses aimed at allowing relief workers to vaccinate Palestinian children against reemergent polio.

Israel’s strike on the Safad school in Gaza City killed at least 11 people, including a woman and a girl, a spokesperson for Gaza’s civil defense agency told Agence France-Presse.

The Israeli military claimed it was targeting a “Hamas command center” inside the school, which — like other Gaza schools that remain standing — was being used as a shelter for people displaced by Israel’s nearly 11-month assault.

The Euro-Mediterranean Human Rights Monitor said in a statement Sunday that “Israeli aircraft and tanks continue to bomb the central Gaza Strip, the area where the polio vaccination campaign has begun.”

“Along with the ongoing shelling in various parts of the strip, these Israeli military attacks have coincided with the peak of families’ movement with their children towards the designated vaccination centers,” the group said. “Some of these attacks have even targeted locations near the vaccination centers, endangering the progress of the vaccination process that is required to stop the poliovirus from spreading among Palestinian children in the besieged enclave.”