PAULSBORO, N.J. (AP) — A freight train derailed Friday on a railroad bridge that has had problems before, toppling tanker cars partially into a creek and causing a leak of hazardous gas that was blamed for sickening dozens of people, authorities said.

Members of the National Transportation Safety Board arrived in New Jersey on Friday afternoon to investigate. They will try to determine whether the derailment was caused by a problem with the bridge or if the derailment was to blame for the bridge's partial collapse.

A delicate operation lies ahead, as a huge crane was being brought from New York Harbor to pick up the dangling tanker cars.