Syria chemical attack death toll now at 72

World leaders from Washington to London to Istanbul expressed shock and outrage Tuesday at reports of a suspected chemical attack in northwestern Syria that killed scores of civilians, with one UK official suggesting the incident amounted to a war crime.

The death toll from chemical attack in northern Syria rose to 72 on Wednesday as activists and rescue workers found more terrified survivors hiding in shelters near the site of the harrowing assault, one of the deadliest in Syria’s civil war.

Earlier, the Britain-based Syrian Observatory for Human Rights said at least 58 people died, including 11 children, in the early morning attack in the town of Khan Sheikhoun, which witnesses said was carried out by Sukhoi jets operated by the Russian and Syrian governments.

Many casualties were the result of asphyxiation, doctors said. Videos on social media purporting to be from the scene show people, including children, who appear unresponsive; others struggle to breathe or wear oxygen masks.

Turkey said it dispatched 30 ambulances to Idlib following chlorine gas attacks in the northwestern province, the Turkish Anadolu news agency reported.

The United Nations, world leaders and human rights groups are pushing for sanctions and a new global outlook on Syria in the wake of its suspected deadly chemical attack that the White House describes as a wake-up call to “the civilized world.”

“Once again the Syrian regime will deny the evidence of its responsibility for this massacre,” French President François Hollande said in a statement.

“Bombing your own civilians with chemical weapons is unquestionably a war crime, and they must be held to account,” declared British Foreign Minister Boris Johnson.

The Turkish foreign minister, Mevlut Cavusoglu, said the attack was a crime against humanity that could derail the fragile Syrian peace process.

An emergency UN Security Council session has been scheduled for Wednesday morning, according to US Ambassador to the UN Nikki Haley.

Syrian military denies responsibility

The Syrian army “categorically denies the use of chemical and poisonous material in Khan Sheikhoun,” the General Command said in a statement. “The Syrian army holds the terrorist groups and those supporting them responsible for the use of chemical and poisonous material and for the careless wasting of innocent civilians’ lives to achieve their despicable goals and agendas,” the statement said.

Pope Francis appeals to ‘conscience’ of culprits

Pope Francis has called on countries supporting atrocities in Syria to examine their consciences as Russia vows to continue its backing for Bashar al-Assad.

The Catholic leader said he was horrified by the suspected chemical weapons attack in the rebel-held town on Khan Sheikhoun, calling it an “unacceptable massacre” of innocent civilians.

“We look on horrified by the recent events in Syria,” he told tens of thousands of people in St Peter’s Square during his weekly audience.