WOONSOCKET — Four boys, who told the police they were merely trying to illuminate the inside of the former Roller Kingdom roller rink on Diamond Hill Road, were charged last night with second-degree arson in connection with a fire that turned the rink into a hulking shell.

The blaze, which was discovered at 5:30 p.m., took more than five hours to extinguish, and closed the road for six hours.

Police Lt. Timothy Paul said the boys had broken into the former rink the day before, and when they returned yesterday tried to make more light by burning paper plates, using paint thinner as an accelerant.

When the fire grew, the boys ran from the scene but didn’t realize how big the fire was until they looked back and saw smoke and went to the Walmart next door to call the Fire Department.

The police gave the boys’ ages as 12, 13, and two 15-year-olds.