From Longman Dictionary of Contemporary Englishfriendly firefriendly firePMWbombs, bullets etc that accidentally kill people who are fighting on the same side → friendly
Examples from the Corpus
friendly fire• But what really hurts is the friendly fire.• One step forward.New hope for truth about the victims of friendly fire.• Wednesday he re-introduced Kevin Pollak, injured and disfigured by friendly fire in the Gulf War.• Few details were released of the precise circumstances of the friendly fire incidents which caused the casualties. 