RAW VIDEO: In this U.S. Coast Guard video, a USCG boat fires on a Japanese ship adrift off the coast of Alaska in an attempt to sink the unmanned vessel and clear it from shipping lanes.
Updated at 10:30 a.m. ET: A fishing vessel set adrift by the tsunami in Japan has sunk in the Gulf of Alaska after a cutter fired at it, The Coast Guard said.
Petty Officer David Moseley told msnbc.com that the vessel caught fire and took on water after the Coast Guard Cutter Anacapa fired its 25mm cannon at the derelict ship on Thursday, aiming to sink what it called a threat to shipping.
The ship sank to the bottom of the ocean after it was pummeled at by high-explosive ammunition, the Vancouver Sun reported Friday morning. Explosives were fired at the stricken vessel in a "slow and deliberate" manner to ensure accuracy, Veronica Colbath, Coast Guard public affairs officer, said, The Sun reported.
It took about four hours for the ship to vanish into the water, said Chief Petty Officer Kip Wadlow in Juneau. It sank into waters more than 6,000 feet deep, about 180 miles west of the southeast Alaska coast, the Coast Guard said.
Citing a Coast Guard spokesman, the Associated Press reported the firing began after a brief delay caused by a Canadian ship that wanted to salvage the Ryou-un Maru -- but then quickly found it it wasn't able to tow it back to shore.
Besides clearing a shipping lane, sinking the nearly 200-foot-long vessel provides the Anacapa crew "a great way for them to put their skills to use," Coast Guard spokesman Kip Wadlow told msnbc.com from Juneau, Alaska.
Wadlow said the drifting vessel makes shipping in the area extremely dangerous. "There's no crew on board, it doesn't have any light ... and it's in a high volume shipping lane," he noted.
The Coast Guard fired cannons on the ship that had drifted to the Gulf of Alaska after becoming unmoored after the Japan tsunami, choosing to sink the vessel rather than having it pose a risk to maritime traffic. NBC's Savannah Guthrie reports.
The fishing boat, which was in port waiting to be scrapped when the tsunami took it out to sea, is far enough away that any fuel on board would not make it to shore, Wadlow added. The Coast Guard later elaborated that it appeared to be carrying little fuel since it was riding high in the water, the AP reported.
A Coast Guard C-130 was flying over the area to warn away any nearby ships for what is described as a "live fire exercise."
Dropping crews aboard the boat is too dangerous, Wadlow said, and "the owner no longer wants it."
But that didn't stop the Bernice C from trying to make some money off the rusty vessel.
Based in Petersburg, Alaska, the Anacapa arrived Wednesday night alongside the Ryou-un Maru, which entered U.S. waters on April 1. The ship was moored at a harbor in Hachinohe, Japan, when the earthquake and tsunami hit on March 11, 2011.
The vessel is the first large object to reach North America following the tsunami. Smaller objects have been found on U.S. coasts but much more debris is expected to make its way via currents to U.S. and Canadian beaches by 2014.
State officials have been working with federal counterparts to gauge the danger of debris including material affected by a damaged nuclear power plant, to see if Alaska residents, seafood or wild game could be affected.
The Associated Press contributed to this report.
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