Father loses 9-month-old twins in Syrian chemical attack

— -- Abdel Hameed al-Youssef sat in a car, cradling his 9-month-old twins wrapped in white.

Their faces were sapped of life, victims of a chemical attack in Syria on Tuesday that took the lives at least 72 civilians, including at least 20 children, according to the Syrian Observatory for Human Rights.

"I was right beside them. I took them outside with their mother," al-Youssef, 29, told The Associated Press. "They were conscious, but 10 minutes later, we could smell [the gas], and my children couldn't handle it anymore. I left them to the medics and went to find my family."

He told the AP that he lost other family members in the horrific attack, which was just one in a series of chemical attacks in war-torn Syria.

"My brother Yasser is dead. I couldn't save him. So is my brother Abdel Kareem. My nephew Yasser Mohammad, I couldn't save. Ammar my nephew, I couldn't save. Shaimaa my niece, I couldn't save. My sister-in-law, they all died. Two of our workers, 11 of another family died in their own land. Khaled and his wife, Abounajib, his wife and his daughter," al-Youssef told the AP.

His family is not alone in suffering.

Abdullah al-Hussein, a volunteer with Syria Civil Defense, known as the White Helmets, told ABC News that an entire family was found dead in a shelter, killed by the gas.

Syria's military denied on Tuesday that it used chemical weapons against civilians, saying it is too "honorable" to carry out such "heinous" crimes.

"The general command of the army and armed forces categorically denies using any chemical or poisonous materials in the town of Khan Sheikhoun in the Idlib countryside today, nor has it used or will it use them in any place or time previously or in the future," the military said in a statement on Facebook.

Many have placed the blame on the Syrian government, including U.S. President Donald Trump, who called Tuesday's attack "heinous actions by the Bashar al-Assad regime."

Trump also faulted his predecessor Barack Obama, suggesting that his administration mishandled the Syria conflict.

U.S. Secretary of Defense Jim Mattis labeled the suspected Syrian chemical attack "a heinous act" and said that it will be "treated as such."

Mattis spoke on camera at the end of a photo opportunity at the Pentagon with the visiting defense minister of Singapore after a reporter shouted a question about the attack.

On Wednesday, Russia blamed Syrian rebels for the attack, saying that the Syrian air force struck a warehouse where opposition militants were storing chemical weapons — a statement that contradicts reports from doctors, residents and White Helmets on the ground.

ABC News' Ben Gittleson, Luis Martinez, and The Associated Press contributed to this report.