KITTERY – Cianbro Corp. said Monday it was mobilizing equipment to salvage the upper section of a crane that toppled into the Piscataqua River near the Portsmouth Naval Shipyard.

No one was injured in the Sunday afternoon accident, which was blamed on a failure in a floating crane that was being used by the Pittsfield-based contractor to lift the 117-ton section of a salvage crane onto a barge for transit.

The contractor said it was trying to determine what caused the largest barge-mounted crane in the state to fail.

The accident punctured the floating crane’s fuel tank, spilling up to 175 gallons of diesel fuel into the river. The shipyard’s oil spill recovery team deployed containment booms around the area.

Officials said the salvage crane’s upper section, or house, fell into 30 feet of water and did not pose a hazard to navigation.

The shipyard said the time frame for completion of the salvage crane removal has not been determined.