A school security guard videotaped a teenage boy in the restroom at Roosevelt High School, then posted the footage on a mobile app for videos, Nassau police said.

Authorities arrested Daniel Williams, 24, of West Babylon, and charged him with felony second-degree unlawful surveillance and endangering the welfare of a child, a misdemeanor.

Williams is accused of videotaping the 16-year-old student as he used a restroom stall on Tuesday morning. Police said he sent the footage with Snapchat, an increasingly popular mobile messaging app for images, which self-destruct after the receiver views them.

Williams declined to comment when reached Wednesday evening.

After the incident, the student notified school administrators, who alerted police, said Det. Lt. Rich LeBrun, a police spokesman.

Williams has been a security guard for two years, LeBrun said. Detectives are trying to determine how many people were sent the video, he said.

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A spokeswoman for the school district said Williams was suspended with pay and ordered not to go on school grounds unless he gets approval.

Williams was released with an appearance ticket for April 11 at First District Court in Hempstead.