A truck carrying rags soaked in paint thinner spontaneously combusted on U.S. Interstate 20 early Friday morning, blocking an off-ramp and causing school authorities to close the Georgia Perimeter College Newton campus for the day. According to Newton County Fire Department Deputy Chief Tim Smith, the driver of the tractor-trailer truck noticed smoke in his rearview mirror around 2:30 a.m. and pulled over on exit 98, the exit leading to GPC's Newton campus. No other vehicles were involved or damaged.