Prank gone wrong

I've been doing some pranks to family around the house out of boredom, which have been great fun but 4 days ago I took it a step further and wanted to make my elderly neighbour jump. He is always pottering around in the garden at this time of year and I proceeded to put my plan in to action! I used an air horn from a football game I'd been to get a jump out of him (all for lols) I had quick look over the garden fence to see where he was and waited until the time was right for me to pop my arm over and let rip at full pelt, only he was entering his green house and ended up falling through a pane of glass which resulted in him going to hospital with a fractured arm and cuts to his hands, shoulder and face. I only heard the smashing of glass and ran, his wife had told my mother after she had asked about the ambulance she had seen outside their home. I have said nothing about what had happened as he has no idea it was me but I feel guilty yet also don't want to face the backlash. Is it normal to not own up to things and white lie?