Investigators secretly detonated a working replica of the car bomb used in the failed Times Square terror attack, creating a large explosion that destroyed other vehicles and scattered flaming debris, law enforcement officials said July 20. The test in central Pennsylvania showed that the homemade bomb, had it been constructed and detonated properly, would have killed or wounded an untold number of pedestrians and damaged buildings along the block in New York City where the car was abandoned by the suspect May 1, the officials said. New York Police Department bomb experts later determined the suspect had used a type of fertilizer that was not volatile enough to explode like the ammonium nitrate grade fertilizer used in previous terrorist bombings. The New York police commissioner said July 20 that investigators believe the suspect purposely “dumbed down” the bomb — using the less potent fertilizer and M88 firecrackers — to avoid detection. For the test, the officials said the investigators also used a Nissan Pathfinder but rigged it with the higher grade fertilizer and more sophisticated components.