A United Nations-appointed commission on Wednesday said that Syrian President Bashar al-Assad’s Air Force was responsible for the sarin gas attack that killed over 100 people, including children, in Idlib province in April, AP reported. The investigators also appealed to the Syrian government to protect civilians when it strikes at Islamic State militants in the country.

“We have analyzed all the other interpretations of who might have conducted the attack,” Commission of Inquiry on Syria Chairman Paulo Pinheiro said at a press conference in Geneva. “We concluded that this attack was perpetrated by the Syrian Air Force.”

The commission’s report is based on information accessed from satellite images, video, photos, medical records, and over 300 interviews, from March through July this year. The report described the Syrian air force’s actions as “war crimes of using chemical weapons and indiscriminate attacks in a civilian inhabited area.”