Scared to death at a city park. Overlooking Belfast Harbor

Me and a friend were sitting at the city park when we heard something like a sonic boom, then a splash,then another boom.  My friend told me to stand behind him and look over the water.  When I did I saw a triangler shape swaying in the sky.  My friend told me to look at him and when I did I saw a white dot on his head.  I followed it to the triagle.  We got up and headed out of the park. We walked about 5 feet and stopped to look behind us.  It was gone.  Then there was a bright light above our head and we looked up.  The next think we know we had walked about 2oo feet and didn't know it.  That 200feet I have no idea what happened.