Coast Guard Adm. Thad Allen says crews are shooting chemical dispersants at oil that began leaking when a saw became stuck in the latest attempt to contain the Gulf oil gusher.
The saw snagged as it was cutting through a pipe on a busted well. Allen said Wednesday the goal is to free the saw and finish the cut later in the day.
This is the second major cut in the effort to contain, not plug, the nation's worst spill.
Submersible robots are working on the risky attempt to control the gusher, while the crude on the surface is spreading.
BP's latest effort involves a set of tools akin to an oversized deli slicer and garden shears to break away the broken riser pipe. Engineers will then try to position a cap over the well's opening.
The risk comes from an increase in the flow of leaking oil. Even if successful, the move will temporarily allow about 20 percent more oil to flow. That's at least 100,000 gallons a day, on top of an estimated 500,000 to one million gallons.
Allen says the first cut with giant shears was successful overnight.
The best chance at plugging the leak involves a relief well that is at least two months from completion.
In the Florida panhandle, crews have shored up miles of boom to protect the white sands of Pensacola Beach from an oil sheen spotted about nine miles offshore. It could make landfall as early as Wednesday.
Florida would be the fourth state hit. Crude has already been reported along barrier islands in Alabama and Mississippi, and it has affected some 125 miles of Louisiana coastline.
BP's stock plummeted Tuesday as the federal government announced criminal and civil investigations into the spill.
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