Pope Francis and the World Council of Churches general secretary Rev. Olav Fykse Tveit have strongly condemned the Aug. 17 terrorist attack on Barcelona, in which at least 13 people died and more than a hundred were injured.

The carnage took place on the famed La Ramblas boulevard in the Catalan capital when a white van sped onto the historic promenade, on which tourists thronged, mowing down horror-stricken people.

The Pope expressed his "deepest sympathy" for the victims of the terrorist attack on Barcelona with a telegram to the city's Catholic Archbishop, Cardinal Juan José Omella.

The telegram was signed by Cardinal Secretary of State, Pietro Parolin and in it Francis condemned the "blind violence" manifested in the attack, saying it is "a grave offense to the Creator."

He prayed for those who "lost their lives to such an inhuman act".

"In these moments of sorrow and pain," the Pope "wishes also to offer his support and closeness to the many injured, to their families, and to all Catalan and Spanish society," it read.

Tveit called for an end to attacks on innocent people and a unified voice of justice and peace across the world.

"We must stand together in the face of terror attacks that we can't understand or predict," the WCC leader said. "We know we live in a dangerous time. What we can be sure of, is that the God of life wants us all to enjoy the fullness of life equally."

Tveit expressed condolences to those who lost loved ones, those struggling with injuries, and responders who are still treating people at the traumatic scene.

On the Twitter social media tool, the Archbishop of Canterbury Justin Welby said: "Full of sorrow for those affected by the attack in Barcelona, Christ give eternal light and peace and hope to the bereaved and injured."

The driver of the van that ploughed into crowds in Barcelona, killing 13 people, was one of five men shot dead by police in a Catalan seaside resort hours later, two Spanish newspapers reported on Aug. 18, but there was no immediate confirmation of the reports, Reuters news agency reported