STEAMBOAT SPRINGS, Colo. (CBS4) – Exhaust from a coal-rolling truck covered a crowd at a “March For Our Lives” event in Steamboat Springs on Saturday.

Witnesses say trucks blasted the marchers more than once.

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(credit: CBS)

A 20-year-old was cited not long after.

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The latest ticket was given to a high schooler.

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Police say they’ve identified a third vehicle that was spitting out the exhaust, and are working to find the driver.