WASHINGTON, DC (CNA/EWTN News) - Religious and political leaders have renewed calls for peace as they decried dozens of reported civilian deaths by poison gas this week in the Syrian conflict.  

"The chemical attack in Syria on April 4 shocks the soul. The many innocent lives targeted by these terrible tools of war cry out for humanity's protection," Cardinal Daniel DiNardo, president of the U.S. Conference of Catholic Bishops, said Wednesday.

At least 70 people, including children, were reportedly killed in Idlib, Syria on Tuesday by deadly gas after the neighborhood of Khan Sheikhoun was bombed, reportedly by forces of Syrian President Bashar al-Assad.

There have been around 200 reported chemical attacks in Syria, the medical care group UOSSM noted. The conflict there has lasted six years. Last year, the UN reported that Syrian government forces and ISIS had used chemical weapons on multiple occasions in 2014 and 2015. The use of chemical weapons is a war crime and violates international law.

"If confirmed, this would constitute the single largest chemical weapons attack in [Syria] since the attack on Eastern Ghouta in August 2013," Kim Won-Soo, the UN's High Representative for Disarmament Affairs, said of Tuesday's incident.

UOSSM, which had doctors working in the targeted area, reported that victims of Tuesday's bombing were showing symptoms of asphyxiation, foaming of the mouth, and "severe Dyspnoea." 

"Medical facilities are overwhelmed with patients and unequipped to handle chemical attacks of this magnitude," they stated, adding that "many area hospitals have been put out of service, further complicating the situation."

Dr. Monzer Yazji, president of UOSSM USA, reporting seeing a "major shortage in doctors, staff, and facilities inside Syria" in a trip there last week. "The attack today has left us all paralyzed. We are unable to properly treat the injured," Dr. Yazji said.

Reporting on the attack, one activist witness said white smoke covered the vicinity after a bomb dropped, according to Reuters.

However, the Syrian government has denied using chemical weapons on the area, and its Russian allies have claimed that a bomb hit a rebel-held factory manufacturing chemical weapons, which then dispelled the gas.

The UN on Tuesday reported that details of the attack were "still coming in" and that "the attack had reportedly been carried out through an air strike on a residential area" but "the means of delivery could not be confirmed."

Secretary of State Rex Tillerson on Tuesday condemned the "chemical weapons attack" which he said was "the third allegation of the use of such weapons in the past month alone." President Donald Trump said the attack "crossed a lot of lines" in a Wednesday joint press conference in the White House Rose Garden, with King Abdullah II of Jordan.

"While we continue to monitor the terrible situation, it is clear that this is how Bashar al-Assad operates: with brutal, unabashed barbarism," he said of the Syrian president. "Those who defend and support him, including Russia and Iran, should have no illusions about Assad or his intentions," he added, saying that "as the self-proclaimed guarantors to the ceasefire negotiated in Astana, Russia and Iran also bear great moral responsibility for these deaths."

The advocacy group In Defense of Christians also condemned the attack.

"IDC condemns in the strongest terms the brutal violence and tactics of torture being used by Syrian President Bashar al-Assad's regime with the support of Russian and Iranian forces against civilians in Syria," IDC executive director Philippe Nassif stated.

Religious and political leaders have called for prayer, for the perpetrators to be held accountable, and for a peaceful end to the conflict which has lasted for over six years. 

"In this season of Lent when Christians draw near to the suffering of Christ, let us match the horrific indifference shown for innocent life with a fervent prayer for love to break through the evil," Cardinal DiNardo said. "Let us also match our prayer with a faithful witness to suffering so that no life at risk is forgotten."

Pope Francis condemned the attack and offered his prayers "for the victims and their families."

"I appeal to the conscience of those who have political responsibility, locally and internationally, so that this tragedy may come to an end and relief be brought to that beloved population who for too long have been devastated by war," he said.

The use of poison gas on civilians is a war crime, but under international criminal law the perpetrator is not known right now with complete certainty, Professor Robert Destro, an international law expert at the Catholic University of America's Columbus School of Law, explained to CNA.

"We need to know who did it," he insisted. "There are certain things that you are just not allowed to do."

There are several actions countries could take to find the perpetrators and hold them accountable, he said, one approach being to use international criminal law, filing an indictment against the guilty party in an international criminal tribunal.

However, for this to take place, world leaders like the U.S., China, and Russia would have to come together, as "the U.S. cannot hold them responsible by itself."

The international community must start meeting to determine not the best interests of particular countries, he said, but rather "what is in the best interest of people who live in the neighborhood" in Syria.