New York ? The New York City Fire Department on Friday will release some 900 hours of radio transmissions from Sept. 11, 2001 and oral histories given by 500 fire personnel in the days after the attack.

While the events of 9-11 already have been examined by a national commission and several oversight agencies, the documents and tapes will again focus attention on that day.

The oral histories will be in the form of written transcripts of interviews with firefighters, superior officers, medical workers and other department employees, made in the weeks after the attack on the World Trade Center.

The radio transmissions are recordings of conversations between fire alarm dispatchers and units in the field. They will not include civilian calls for help.