Security is being tightened around New York City ahead of Sunday's 9/11 anniversary.
The NYPD has no evidence of terror threats against New York City for the anniversary of Sept. 11, but is taking precautions as if a plot is underway, Police Commissioner Ray Kelly said Wednesday.
Information uncovered at Osama bin Laden's compound after his death shows al-Qaida considered attacking trains on the 10th anniversary of the tragedy.
"For that reason alone, we need to take precautions as if an actual plot is under way," Kelly said.
Starting Saturday night, the NYPD plans to form a frozen zone around the World Trade Center site ahead of the Sunday ceremony.
Thousands of extra officers will descend on the area, and the security also will include 450 surveillance cameras trained on the site, Kelly said. Manhole covers will also be sealed.
The World Trade Center gathering is one of more than 30 commemorative events scheduled for the week that the department is laboring to protect, Kelly said.
"We don't presume that ground zero alone is a potential target," the commissioner said. "That would be shortsighted."
The department also will deploy "quick strike reaction forces" to respond to potential threats outside Lower Manhattan, Kelly said.