COLORADO SPRINGS, Colo. -- Copper wire thieves who are sometimes disguised as utility workers in vests and hard hats have stripped wire from 291 light poles during the past three months, costing the city's utility some $658,000 in repairs.

A global demand for metal has cause a spike in scrap metal prices. Copper thieves have usually targeted construction sites, but since May have been plundering light poles, Colorado Springs Utilities spokesman Steve Berry said.

The cost of the thefts could force an increase in utility rates.

"Obviously, if this continues we can only do so much with our current budget," Berry said.

On Tuesday night, thieves pried open the backs of 24 light poles and pulled out the plastic-sheathed wires. Line technician Pat Palacol said they usually hit several poles along a single street.

"They took this whole interchange," Palacol said Wednesday afternoon, standing near the intersection of U.S. 24 and Union Boulevard.

To prevent thefts, workers are installing special bolts on the poles.