Let me first state that i was not able to see anything visually, I am not sure if this even qualifies as a UFO sighting but I did not know who else to report this to. It was about 5:00pm yesterday afternoon, I was standing outside on my back porch, the sky was clear I had been sitting in the sun throughout the day and pulling weeds out of the garden earlier. So as I was standing there, out of nowhere the was a loud sound similar to a jet or a large plane at first but it suddenly got much louder and sounded like a missile or a bomb dropping? I have never heard one personally but it was the only comparison I can think of right now.? It was so deafeningly loud and I could feel the base from it in my body and in the ground. I was so afraid that our entire city was about to be blown up that I ran inside and tried to get my family into the basement. My mother and girlfriend heard the noise as well It sounded like something getting closer and closer and then there was nothing, i kept wairing for a shockwave or something, i was terified. After I felt like it was okay and caught my breath, I went back upstairs to be laughed at and told it was probably just a plane, I looked around, out front , out back, every direction and I could not see a plane or vapour trail of any kind anywhere. We live close to a local airport so I hear a lot of planes and have been to air shows and am very familiar with the sound of commercial jets and military jets and small air crafts, the sound I heard was nothing like that or nothing I have ever heard in person. I contacted my father in Pickering , 2 cities to the west , about 40km away and asked him if he had heard anything, he stated not at all other than the Pickering nuclear power plant air raid sirens being tested in the late morning that day. I have no idea if there is any correlation or reason that this sound occurred on the same day, I just thought that small detail could be relevant or may be the underlying cause.? I wish I could have seen the object or get some answers as to what could have caused such a loud sound or what kind of object could even create that sound, I would also like to know if anyone else in my area reported this noise? I am available for further questioning but I am currently restricted from leaving my residence I'm accordance to my probation right now, I have an ankle bracelet on so I'm not able to leave but you can reach me by phone and email. I do not answer to blocked callers or private numbers, I find it helpful to screen my calls. Thank you in advance, and I hope this letter is not a waste of time..