The U.S. military said Tuesday it struck a mosque that had allegedly been used as an Islamic State control center, as American-allied Syrian forces battled the extremists in their last stronghold in eastern Syria amid reports of more civilian casualties.

The U.S.-led coalition said warplanes struck the mosque in the small town of Baghouz on Monday in support of the Kurdish-led Syrian Democratic Forces. It said the airstrike occurred as ISIS was using the mosque to direct attacks and employ suicide car bombs against the SDF.

“This mosque lost its protected status when ISIS deliberately chose to use it as a command and control center,” said the coalition’s deputy commander, Maj. Gen. Christopher Ghika.

Read more: Military Times