NORWICH, Vt. (AP) — Vermont State Police are investigating how a large boulder found its way into the middle of an interstate highway, damaging two vehicles that crashed into it.

Police say they responded to calls of a large rock in the middle of the southbound lanes of Interstate 91 in Norwich a little after 3 a.m. Saturday.

When they arrived, they found a boulder approximately the width of a travel lane and too heavy for a person to carry. Police say they don’t know how the boulder got in the road and are asking the public for information.

Troopers say two sport utility vehicles sustained heavy front-end damage when the drove into the boulder, but nobody was injured.