SAN DIEGO -- A rash of burglaries targeting jewelry at JCPenney stores in Southern California -- including three in San Diego County -- may coincide with recent spikes in the price of gold, authorities said Monday.

The first break-in attributed to the ring occurred Sept. 13, 2006, in Palm Desert. Thereafter, the thieves seemingly were inactive until a heist last Dec. 6 in Westminster, said Jim Amormino of the Orange County Sheriff's Department.

Other stores hit were in Thousand Oaks on Jan. 3; Northridge on Jan. 5; Santa Ana on Jan. 18; Cupertino on Jan 26; Pleasanton on Jan. 26; El Cajon on April 4; Escondido last Wednesday; and Laguna Hills and Carlsbad last Friday, Amormino said.

The burglars have gotten away with between $200,000 and $400,000 worth of gold during each crime, with total losses estimated at $2.5 million, Amormino said.

They pry open emergency doors or jimmy locks to gain entry to the stores. In some cases, there is no outward sign of a break-in and alarms that went off were deemed false threats, Amormino said.

Authorities have simply been unable to get to the stores in time to catch the crooks, who carry out their crimes rapidly and efficiently, Amormino said.

"They definitely case the places and were familiar with the stores they hit," Amormino said. "They knew exactly where to go and go in quickly and out quickly. They are very selective in what they took. In many cases, they left more expensive jewelry (such as) diamond rings."

The bandits use crowbars to rake the loot from cases after cutting open lock mechanisms, he said. The men wear ski masks with hoods over their heads, concealing their faces. Several of them appear to be of average height and weight, and one is heavier, Amormino said.

Amormino said the thieves seem to be going after gold -- which currently costs about $1,000 an ounce -- because of its increasing value in recent years. "Since (the price of) gold has been up, there have been nine burglaries in five months," he said. "That's a lot."

Investigators believe the thieves either melt down the stolen jewelry or sell it through fencing, Amormino said.

A $20,000 reward has been offered for information leading to an arrest or conviction of the burglars.