(NewsNation) — A video of Navy SEAL recruits on California’s San Clemente Island being tear gassed while ordered to sing “Happy Birthday” has triggered an investigation into its selection course.

The video shows trainees being exposed to tear gas at an amount and length that surpasses regulations, which the investigation will examine.

Matthew Cole, who acquired the video, says most people who breathe in tear gas that close have trouble breathing for at least a week.

“Even the best of the best have some rules and regulations, right? You may be in SEAL Team Six, but you are not allowed to murder someone illegally,” Cole told “On Balance” on Wednesday night.

“There’s a lawful killing on the battlefield. And then there are unlawful killings on the battlefield. The question is: This video is a small example of what has been two decades of drift within the SEALS with following rules and regulations.”