Officials are looking into whether suspicious packages investigated today in Brooklyn, Newark, Philadelphia and the United Kingdom were part of a dry run for a mail bomb plot.

Three cargo planes, one in Newark and two in Philadelphia, have been searched, as well as a delivery truck that made its way across the city via the Queensboro Bridge – eventually making it to MetroTech in Brooklyn.

Two items were examined and cleared there – one envelope from Yemen and a similiar-looking package.

The envelope, which was filled with bank receipts, came from John F. Kennedy International Airport and was addressed to JPMorgan Chase's location at MetroTech.

So far all packages found in the United States have been cleared for explosives.

Police Commissioner Ray Kelly said today's events have not heightened security levels.

"We're at a high level of vigilance here. You know, we believe, I believe, the threat has not abated," said the police commissioner. "The threat has been relatively consistent since 9/11. We've had 11 plots here. And we continue to operate under that premise -- that New York City is at risk."

A suspicious package in the United Kingdom prompted the searches. Officials say a toner cartridge with wires and white powder attached was discovered during a routine cargo screening at an airport two hours north of London. Tests on the device came back negative for explosives.

Meanwhile, FedEx has confiscated a package in Dubai that was also shipped from Yemen.
The company says it has embargoed all shipments from Dubai.