Sept. 29, 2010 -- The bomb planted in Times Square last spring could have been "devastating" and killed or injured dozens of people, according to an assessment of a government explosion of a mock "bomb" based on Faisal Shahzad's failed device.
Watch "World News with Diane Sawyer" for more on this story tonight on ABC.
Video of the Joint Terrorism Task Force's explosion, released today, shows how much damage a successful device could have caused.
Bomb experts said that while it is unlikely the resulting blast would have taken down any buildings, glass and twisted metal shooting out from the vehicle housing the bomb would have formed deadly shrapnel.
People in close proximity to the car could have been injured or killed by the fire and blast force, the experts said. In addition, it is possible that there would have been injuries from broken glass and falling debris from adjacent buildings.
The bomb test was revealed in the Justice Department's sentencing memorandum for Shahzad, filed today.
"On June 29, 2010, the JTTF conducted a controlled detonation of its bomb after it was placed in the back of a vehicle identical to the one Shahzad used," the memorandum said. "The JTTF also placed other vehicles nearby in order to measure the explosive effects of the bomb. While it is impossible to calculate precisely the impact of Shahzad's bomb had it detonated, the controlled detonation conducted by the JTTF demonstrated that those effects would have been devastating to the surrounding area."
Shahzad Cold and Calculating, According to Justice Dept. Filing
The filing also portrayed Shahzad, who pleaded guilty in June in connection with the plot, as cold, calculating and intent on killing as many people as possible.
The Justice Department said he used the Internet to "measure the size of crowds in one of the most popular locations in the world in order to maximize the number of innocent victims.
"The premeditated attempt to kill and maim scores of unsuspecting innocent men, women and children with a homemade bomb can only be described as utterly reprehensible," the sentencing memo said.
Shahzad Believed Bomb Could Kill 40 People
"Following his arrest, Shahzad waived his Miranda rights and stated, among other things, that he believed his bomb would have killed at least 40 people, and that, if he had not been arrested, he planned to detonate a second bomb in New York City two weeks later," the Justice Department said.
The department's memo also noted that Shahzad was in regular contact with the Pakistani Taliban (TTP).
"Shahzad also maintained regular contact with members of the TTP over the Internet," the Justice Department said. "Using software programs that were installed on his laptop computer while he was in Pakistan, Shahzad and the TTP were able to exchange information about the bomb he was building, the vehicle he had purchased, and other topics."
The government is seeking life imprisonment for the Shahzad.