SAN FRANCISCO - A crane tipped over while working on the new eastern span of the San Francisco-Oakland Bay Bridge on Thursday, but there were no injuries and nothing leaked into the bay, authorities said.

The crane was on a barge underneath the new span helping to remove a temporary support structure and was holding a piece of the structure when it fell around noon, according to bridge spokesman Andrew Gordon.

Gordon said officials were investigating what caused the crane to tip over and whether the new span was damaged.

The new bridge is expected to open over Labor Day weekend. It will connect Oakland to Treasure Island and replace a structure that was damaged during the 1989 Loma Prieta earthquake.

The supports the crane was taking down were installed years ago to hold up the bridge superstructure during construction, according to Bay Area Toll Authority spokesman John Goodwin.

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