Pope Francis on Sunday called the invasion and bombing of Ukraine by Russian forces “barbaric.”

During his blessing at the Vatican, Pope Francis cited how the invasion is an “unacceptable armed aggression” and that it must be stopped. Russia’s bombing of children’s hospitals and innocent civilians has “no valid strategic reason,” he said.

“In the name of God, let the cry of the suffering people be heard, and let the bombings and attacks stop,” Pope Francis said.

“In the name of God, I ask you, stop this massacre,” he added.

On Wednesday, Russia bombed a children’s and maternity hospital in Mariupol, a city that has seen extensive damage from attacks. The bombing killed at least three people, which includes a 6-year-old girl. There have been an estimated 1,500 deaths in Mariupol.

Pope Francis called Mariupol a “city of martyrs.” The destruction has left thousands in the city without food, water, electricity or heat.

“With pain in my heart I join my voice to that of the common people, who implore an end to the war,” Pope Francis said.

“Let there be a real and decisive focus on negotiation, and let the humanitarian corridors be effective and safe,” he said.