CEDAR FALLS, Iowa (AP) -

Authorities have safely detonated a pipe bomb found in a Cedar Falls neighborhood.

The Waterloo-Cedar Falls Courier reports a bomb squad from the Waterloo Police Department used a robot Tuesday for the controlled explosion in the 2300 block of Royal Drive.

City maintenance workers were clearing storm drains Tuesday when they discovered the pipe bomb. They set it down on a lawn before contacting authorities, who set up a perimeter and evacuated residents.

Police say it's unclear how long the pipe bomb was in the storm drain.