Two bangs heard and one flash seen in northern sky outside Buffalo New York at 22:41 on 9/11/15This report does not involve any flying craft. However I feel compelled to report what I saw and heard.I was walking my dog in my neighborhood and at 10:41 pm I was startled by a loud bang. This did not sound like thunder nor did it sound like any firecracker I have heard. This bang did not sound like a cannon blast nor a gunshot.As I rounded a corner I encountered a neighbor to whom I asked, "Did you hear that" The neighbor said he did and said the bang sounded "metallic" certainly not like thunder. I told the neighbor, "It came from the direction of the fire hall" which was behind me. In other words the bang came from behind me, which was North. The neighbor and I stood for about 60 seconds while we looked to the north. WE did not see or hear anything during that time. I told the neighbor "maybe if we hear it again we might know what it is." I said goodnight to him and continued walking.60 seconds later I turned around and looked North. I was looking straight when I saw a blue-white flash high in the northern sky at about a 75 degree angle from the horizon and heard another bang. The flash looked similar to lightning, but did not spread across the sky like cloud to cloud lightning. The flash was bright but not blindingly so. The flash did not look like a fireball. This second bang sounded identical to the first bang and came after the flash. The second bang did not sound like thunder. I did not see anything shoot upwards from the ground prior to the flash nor did I see anything fall from the sky after the flash.The weather conditions were as follows: It was nighttime with drizzle and overcast skies.