Sea Knight helicopter that crashed last week northwest of Baghdad was shot down, the US military said Wednesday, reversing earlier statements that it appeared to have been due to mechanical failure. The Marine CH-46 troop transport went down northwest of Baghdad on Feb. 7, killing all seven people on board, and an al-Qaida-linked Sunni group claimed responsibility and aired a video. Military officials initially said they believed the crash was due to mechanical failure, but the military announced Wednesday that an investigation showed the crash was "the result of anti-aircraft munitions." "Initial evidence indicated that the CH-46 Sea Knight helicopter went down as a result of mechanical failure. After further investigation using all available means, the cause of the incident has been confirmed to be hostile fire," said Maj. Jeff Pool, a spokesman for the Multi National Force - West.