Times Square Bomb Could Have 'Killed Thousands,' FBI Test Shows

Sources close to the investigation of failed Times Square bomber Faisal Shahzad confirm to Fox News that the FBI tested a correctly constructed version of the explosive device.

Shahzad tried to detonate a car bomb in a Nissan Pathfinder on May 1, but the device fizzled and caused no injuries. But if the bomb had been detonated properly, it could have "killed in the thousands on the high end" and in the "hundreds on the low end," according to a source familiar with the investigation.

While the blast might have been more deadly than the 1995 Oklahoma City bombing that claimed 169 lives, the force of the Times Square explosion would probably not have been as great. The impact of the explosion would have been felt both "upwards and outward," a source said.

A source close to law enforcement said "too many variables" make a precise damage estimate difficult to calculate adding that the bomb would "have caused a lot of damage." Although surrounding office buildings were mostly vacant on the Saturday evening of the planned attack, the high number of tourists on the street would have contributed to the number of causalities.

Two law enforcement officials told The Associated Press that the test explosion destroyed the SUV carrying the properly constructed bomb, damaged other nearby vehicles and scattered flaming debris. The test was conducted in rural Pennsylvania last month.

Shahzad admitted last month to building the homemade bomb and driving it into Times Square in May, officials said.