(CNN) A Chicago teenager who had been shot in the head multiple times was presumed dead and covered with a sheet by paramedics before onlookers noticed he was still moving, police and fire officials said Tuesday.

Erin Carey, a 17-year-old who had just graduated from high school, was shot in the head on Chicago's West Side early Monday and responding paramedics apparently believed he had suffered fatal head wounds, police officials said. They covered his body in a sheet and tended to other victims.

The Chicago Tribune reported that witnesses alerted officers and paramedics that Carey appeared to twitch under the sheet. On police 911 audio, an officer is heard notifying EMS at the scene that Carey appeared to move "from side to side" under the sheet.

"He is responsive," the officer said. "He just moved ... from side to side and his arms. So he is not dead."

"We'll have a unit go down and check on that male," a dispatcher responded.

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