"I ask everyone to continue to help the needy and to pray that dialogue and solidarity may lead to the establishment of a peaceful and fraternal coexistence and offer hope for the country's future," he said, after praying the Angelus with visitors in St. Peter's Square Aug. 29.

He said he had been following the news out of Afghanistan "with great concern."

"I take part in the suffering of those who are grieving for the persons who lost their lives in the suicide attacks that happened last Thursday and of those who are seeking help and protection," he said.

The pope was referring to the Aug. 26 attack when a suicide bomber detonated an explosion among the crowds of people desperate to leave the country at the gate of the Hamid Karzai International Airport. The blast killed at least 169 civilians and 13 U.S. service members, who were set to withdraw from the country by Aug. 31. Thousands of Afghans were seeking to be evacuated as well. The Islamic State claimed responsibility, saying the suicide bomber was targeting Afghan collaborators with the U.S. army.

The pope said, "I entrust the deceased to the mercy of almighty God and I thank those who are striving to help" the people who have been through so much, in particular the women and children.

"In historic moments like this one, we cannot remain indifferent; the history of the church teaches us this," he said.

"As Christians this situation obligates us," he said, launching an appeal to everyone "to intensify your prayer and practice fasting. Prayer and fasting, prayer and penance. This is the moment to do so. I am speaking seriously: intensify your prayer and practice fasting, asking the Lord for mercy and forgiveness."