mow down

イギリスのM25モーターウェイで女性を引いて死亡させた男性が逮捕されました。男性からはアルコールが検出されたようです。
「〈草作物芝など〉を (大鎌機械などで)刈る」という意味のmowですが，その他にdownを伴って「…をなぎ倒す」という意味があります（『プログレッシブ英和中辞典』小学館）。英英辞書にもto kill someone by driving into them fast（LDOCE）と解説があります。ここでは「ひき殺された可能性がある」と解釈できます。（Koyamamoto）

Police arrest driver after woman killed walking along M25
The M25 is closed anti-clockwise from Junction 14 at Heathrow Airport to Junction 12 at Chertsey and Surrey Police warn it will remain shut for 'some time'
A woman killed on Sunday walking along the M25 may have been mown down by a drink driver who then fled the scene, police said.
Officers arrested a man on suspicion of failing to stop following an injury road traffic collision and for providing a positive breath test in connection with the crash.
The man was in the police cells waiting to be quizzed by officers after they found him sat in his black Volkswagen Golf, which he had parked up around three quarters of a mile away from where the woman died.
She was walking along the motorway near the slip road for Junction 13 at Staines-upon Thames, Surrey, at around 2.50am on Sunday when she was knocked down.
http://www.telegraph.co.uk/news/uknews/crime/11338110/Woman-killed-walking-along-M25.html