NEWPORT, R.I. (AP) — Four boys were injured when one climbed onto the roof of an abandoned building that collapsed at a Rhode Island state park, officials said.

A section of the roof of a former stable collapsed under the boy’s weight Monday at Brenton Point State Park in Newport, the state Department of Environmental Management said in a statement. The boy and a 2-by-4-foot slab of concrete fell about 25 feet onto others who were inside the building.

Two of the victims, ages 15 and 16, were taken to a local hospital. Another, age 15, was brought to another hospital by helicopter. A fourth boy, 12, was treated at the scene and released.

The department said it installed fencing around the building more than 10 years ago and has prohibited entry to it for safety reasons. There also are “No trespassing signs” at the property.

The building is known as “The Bells,” part of an abandoned mansion, most of which had been removed.