Order unanimously reversed on the law with costs and application granted. Memorandum: Supreme Court abused its discretion in denying claimant’s application for leave to serve a late notice of claim {see, General Municipal Law § 50-e [5]). Respondent "acquired actual knowledge of the essential facts constituting the claim” shortly after their occurrence (General Municipal Law § 50-e [5]; see, Maurice W. v Onondaga County Dept. of Social Servs., 186 AD2d 986, 987; Pepe v Somers Cent. School Dist., 108 AD2d 799, 800). The injury to claimant’s daughter occurred between classes in the hallway of respondent’s school. She was promptly examined by a school nurse, who summoned an ambulance and completed an accident report. "This report of a child having been seriously injured on school premises should have alerted respondent to the advisability of conducting a thorough and immediate investigation of the incident (see Matter of De Groff v Bethlehem Cent. School Dist., 92 AD2d 702). Having failed to do so, respondent cannot now be heard to complain that the late filing of [the] claim will prejudice its preparation of a defense” (Matter of Urban v Waterford-Half moon Union Free School Dist., 105 AD2d 1022, 1024; see, General Municipal Law § 50-e [5]). (Appeal from Order of Supreme Court, Cayuga County, Contiguglia, J.—Late Notice of Claim.) Present—Denman, P. J., Green, Callahan, Doerr and Boehm, JJ.