A Georgia state trooper was treated and released from a Cleveland, Ohio hospital after a protestor threw an unknown liquid on him during a demonstration near the Republican National Convention.

Captain Mark Perry, a spokesman for the Georgia Department of Public Safety, e-mailed The Atlanta Journal-Constitution on Thursday evening to say the unnamed officer “complained of tingling and numbness.” Perry didn’t know if the protestor had been taken into custody.

It was unclear what caused the numbness — syringes, stickers or something else.

Local media reports said protestors placed yellow stickers on two officers’ arms during a Thursday protest that read, “I am awesome.” Their arms reportedly soon went numb. Police are testing the stickers.

At 5:15, another sticker was placed on a third officer and his neck went numb, according to television stateion WXIX.

It wasn’t clear if the protestors were associated with the Stand Together Against Trump protest. A few dozen demonstrators had gathered in downtown Cleveland.

Cleveland police have now added syringes to the prohibited items list.