LONDON (AP) _ A track and field official struck with a competition hammer died of massive head injuries Tuesday.

Women hammer throwers competing in a national under-20 championships at Bedford Athletic Stadium were warming up Aug. 26 when a hammer _ which fell slightly outside the 40-degree arc of the field _ struck official Norman Stang.

Stang was rushed to the Royal London Hospital and treated, but died Tuesday of the injuries, the Amateur Athletic Association of England said in a statement.

``A hammer was thrown under very controlled and professional conditions. All the audibles and warnings were given, but for some reason Mr. Stang did not see it coming,'' spokesman Ken Oakley said.

The incident is being investigated by the association.