Authorities said speed is the common factor in two separate motorcycle crashes Sunday in Great Smoky Mountains National Park that killed one man and severely injured a second.

Both motorcycle operators had the benefit of approved helmets, according to National Park spokeswoman Dana Soehn.

Lawrence Overby Tuck IV, 24, of Knoxville died at the scene of the 8:38 p.m. crash, Soehn said.

Witnesses told investigating park rangers Tuck slid the northbound motorcycle into a guardrail about 8:38 p.m. just north of the tunnel on the Spur between Gatlinburg and Pigeon Forge. Gatlinburg emergency medical services declared Tuck deceased. A Gatlinburg ambulance transported Tuck to LeConte Medical Center where at 8:53 p.m. he was pronounced dead, Soehn said.

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