Pope Francis said on Wednesday he was horrified by the suspected chemical weapons attack in Syria, calling it an “unacceptable massacre” of innocent civilians.

“We look on horrified by the recent events in Syria,” he told tens of thousands of people in St. Peter’s Square for his weekly general audience. Expressing his “firm deploration of the unacceptable massacre,” the leader of the world’s 1.2 billion Roman Catholics said he was praying for “the defenseless victims, including many children.” Francis appealed to “the consciences of those who hold political power, both at the local and international levels so that these tragedies end.” Russia said on Wednesday contamination in the area was the result of gas leaking from a rebel chemical weapons depot after it was hit by Syrian government airstrikes.