ROME — Pope Francis on Wednesday delivered a strong appeal for a political solution to the war in Syria, condemning what he called “unacceptable carnage” perpetrated this week when an alleged chemical weapons attack killed over 70 people.

“I firmly deplore the unacceptable carnage that took place yesterday in Idlib province, where scores of helpless people, including many children, were killed,” Francis said on Wednesday after his weekly general audience. At the moment, 72 deaths have been confirmed, with 20 children among the victims.

The pontiff then called on the “consciences of those with political responsibility, both locally and internationally, to cease this tragedy and bring relief to that dear population which, for too long, has been exhausted by war.”

Francis also encouraged those bringing aid to victims of the conflict to press on, “even amid insecurity and discomfort.”

It’s still unclear what happened in the rebel-held Syrian town Tuesday at dawn, with reports of chemicals being thrown in an airstrike, and others claiming the toxic gas was stored in a rebel laboratory.

Several global leaders have spoken out about the chemical attack in Syria, including the United States’s Secretary of State, Rex Tillerson, who said that while the U.S. will continue to monitor the situation, “it is clear that this is how Bashar al-Assad operates: With brutal, unabashed barbarism.”

Tillerson also said that those who defend al-Assad, “including Russia and Iran,” should have no illusions about his intentions: “Anyone who uses chemical weapons to attack his own people shows a fundamental disregard for human decency, and must be held accountable.”

UN chief Antonio Guterres said the global body would seek to establish who was to blame for the deadly episode, which he said had “demonstrated that war crimes are going on in Syria.”

The Syrian conflict began six years ago. In April 2016, the United Nations and Arab League Envoy to Syria estimated that 400,000 people had died in the war, but the number has continued to grow.

During Wednesday’s appeal, Francis also referred to the “grave attack” in St. Petersburg, Russia. Monday’s blast in the metro took the life of 14 people and injured almost 50.

“While I entrust to God’s mercy those who have tragically died, I express my spiritual closeness to their families and to all those who suffer because of this tragic event,” Francis said.