Syrian warplanes were out in force Thursday targeting rebel-held areas in northern Syria, with strikes reported in Homs, Idlib, and Aleppo Provinces, and at least 28 reported killed. Among them, reports suggest 20 were civilians.

Strikes appear to have been chiefly targeted at Aleppo Province and the adjoining part of Idlib Province, with 15 of the slain civilians hit in Aleppo. The rebels in his area are largely aligned to Turkey.

Syria is in the process of carrying out an offensive against Islamist rebels in Idlib Province, where most of such groups are operating. They have taken some of the province’s south, including a strategic airbase, but most populated areas remain in rebel hands.

With so many rebels and civilians from rebel-held areas evacuated into Idlib and the surrounding area, the population is even more densely packed than usual, and this makes civilians even more vulnerable to strikes than usual. Given how often strikes end up killing bystanders in Syria even under ideal circumstances, this leaves the population in the north extremely prone to getting killed.