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Police blocked off the University Bridge for several hours Tuesday night while a mysterious box was examined. (CBC)

One of Saskatoon's busiest bridges was closed for almost four hours Tuesday because of a mysterious box that turned out to contain nothing dangerous.

Police said Tuesday they were told about the box, attached to a light standard on the 25th Street Bridge, also known as the University Bridge, around 5:30 p.m. CST.

"Several attempts were made to locate the owner of the box, but all efforts proved futile," police said in their initial news release about the box, issued early Tuesday night.

Bomb squad called in

The police explosive disposal unit was called to evaluate the situation and determined "the box is worthy of further examination."

Several hours later, police said traffic was moving again and there was nothing to worry about in the box.

"The elimination of any threat to public safety was confirmed through the use of an X-ray machine which ruled out the presence of explosives," police said in an update around 9:30 p.m.

The box contained "electronic equipment capable of capturing and transmitting traffic and/or pedestrian data to an unknown location."

"A potential owner for the equipment has not been identified," police said.