Hours after doctors from Syria offered testimony about a chlorine gas attack in the country's northwest to the United Nations Security Council on Thursday, reportedly bringing its members to tears, they informed VICE News that their hospital had just received victims of what appeared to be another chemical weapon strike.

At the meeting, the doctors showed council members footage taken by a field hospital in Sarmin, in Idlib Province, on the night of March 16. The video, which was provided to VICE News, depicted frenetic efforts to resuscitate three young children exhibiting symptoms of chemical exposure. The children were inside their basement home along with their parents and grandmother when a crude barrel bomb landed on the building's air shaft, trapping them inside a cloud of toxic vapor. All members of the family died.

"If there was a dry eye in the room, I didn't see it," US Ambassador Samantha Power, whose mission organized the closed-door session, told reporters afterward. "Those people responsible for these attacks have to be held accountable."

Dr. Mohamed Tennari, the director of the field hospital where the victims of the March 16 attack were treated, told reporters on Thursday that residents in Sarmin heard helicopters that night and then noticed "bleach-like odors."

Another video provided to VICE News shows adult victims of the March 16 attack, including the father of the family, who appears disoriented and struggling to breath shortly before his death. The recording also shows children covering their faces in the hospital waiting room because the stench of chlorine brought on the bodies of the victims was so strong, Tennari said.

Human Rights Watch this week accused Syrian President Bashar al-Assad's government of carrying out the attack as well as at least two others between March 16 and March 31. Witnesses to the other attacks also reported hearing helicopters overhead shortly before bombs fell, which they described producing a smell associated with chlorine. HRW noted that the Syrian government is the only party to the country's four-year civil war that has access to helicopters.

Dr. Zaher Sahloul, head of the Syrian American Medical Society, which helps fund and supply the Sarmin hospital, told VICE News that its staff received eight patients on Thursday night at around 11 PM local time, shortly after the Security Council finished its meeting in New York.

Sahloul said that the victims who showed symptoms of exposure to chemical gases, were sickened when a barrel bomb landed in an area of the city of Idlib called al-Karajat.

"I don't know whether this is coincidental or if it's a kind of message," he said. "Previously the Syrian regime has done these things in response to certain discussions, just to prove they can do anything they want with impunity."

VICE News could not independently confirm the Thursday attack.

In August 2012, US President Barack Obama said that the Assad government's use of chemical weapons would cross a "red line," promising that "there would be enormous consequences if we start seeing movement on the chemical weapons front or the use of chemical weapons." The following August, a chemical attack on a Damascus suburb claimed the lives of as many as 1,400 people. Rights groups blamed the Syrian government, and tensions grew in anticipation of potential US military involvement.

Instead, the Security Council approved a US-Russian brokered plan to remove and destroy Syria's chemical weapons stockpile in September 2013. While that effort has seen some success, chlorine — which is often employed as a cleaning agent — is not considered a chemical weapon on its own. A so-called "dual use" substance, Western council members have repeatedly accused the Syrian government of employing it as a weapon in violation of the Chemical Weapons Convention. If dispersed in a high enough quantity, chlorine can become a deadly "choking agent," causing respiratory failure, chemical burns, and severe vascular problems.

Last September, the Organization for the Prohibition of Chemical Weapons (OPCW) reported "compelling confirmation" that chlorine had been employed "systematically and repeatedly" in Syria. The OPCW is not mandated to assign responsibility for attacks that it investigates, however.

The Security Council passed a resolution in March that condemned the use of chemical weapons in Syria, including chlorine, and threatened further action if future attacks were perpetrated. Russia, Assad's strongest ally on the council, insists that there is a lack of conclusive evidence proving that his government has used chemical weapons. Russia's stance has visibly angered other council members, but its veto effectively prevents the UN from doing more, even if it were to receive conclusive proof from the OPCW that chlorine or another chemical agent was used by Assad's forces in recent attacks.

Russia has meanwhile pointed to Obama's "red line" comments and subsequent lack of military intervention as proof of the Assad government's innocence.

Sahloul said that residents in Sarmin, which is held by the Syrian opposition, are terrorized almost daily by barrel bomb attacks — but the addition of chemical weapons has added an extra element of fear.

"The people there told me that when there are no barrel bombs in the area, they celebrate," he said.