The Israeli military pushed ahead with its offensive in central Gaza on Friday, saying it had killed dozens of militants, including some who had holed up in the premises of a former United Nations school that had been converted into a shelter in the area.

The military said it targeted Hamas fighters at a school compound in Shati, a coastal neighborhood northwest of Gaza City’s downtown. The number of casualties was unclear.

“Hamas systematically, intentionally and strategically places its infrastructure and operates from within civilian areas in full violation of international law and while putting the lives of Gazan civilians at risk,” the Israeli military said in a statement after the strike.

Friday’s attack occurred a day after a strike on a similar school complex nearby in Nuseirat where displaced civilians had taken shelter. The Gazan health authorities said women and children were among those killed in that strike.

Israel on Friday offered a full-throated defense of Thursday’s raid, saying that its forces had targeted 20 to 30 militants who it said were using three classrooms in the former school as a base.

The attacks on the U.N. complexes in central Gaza reflect Israel’s laborious efforts to repacify areas where officials had formerly said Hamas had largely been suppressed.