BRIDGEPORT - Federal officials are investigating a U.S. Postal Service mailbox explosion in Bridgeport.

It happened Monday night near the corner of Madison Avenue and Savoy Street.

Officials say no one was on the street at the time of the explosion. They say it was a low-powder explosive device made with a black powder comparable to what is used in fireworks.

Police searched the area and did not find any other suspicious devices.

The U.S. Postal Inspection Service says it believes this was a random, isolated incident. The service says it doesn't want the public to worry about the safety of the mail.

Federal investigators will take over the case because it was a Postal Service mailbox.

For extended video on the mailbox explosion, watch the clip to the left or click News 12 Extra on Optimum TV channel 612.