SAN FRANCISCO (AP) — Thieves who rammed a stolen SUV into the Wells Fargo History Museum in downtown San Francisco and swiped historic gold nuggets worth roughly $10,000 could face a tough time selling the loot as news of the heist sweeps through the rare metal community, experts say.

Dealers will be on the lookout for nuggets with historical significance that suddenly appear on the market, Northern California rare coin dealer Don Kagin said. The three masked men who smashed the glass doors of the museum, held a security guard at gunpoint and stole the gold from a display case early Tuesday may have difficulty selling the nuggets unless they get melted down, he said.

Melting the precious metal could remove possible markings of the year and place where the nuggets were mined and even the person who unearthed them, said Fred Holabird, a mining geologist and an owner of a rare and unique collectibles business in Reno, Nevada.

"This is such bad news from my viewpoint," he said, calling the theft a tragedy because of the potential for the gold to lose any historical indicators.

Both experts did not speculate on the value of the 4 to 10 ounces of gold that police said was worth about $10,000. But Holabird said the nuggets could be worth two to 10 times the value of gold on the open market, an ounce of which sells for about $1,300.

Selling stolen precious metals is difficult but not impossible. Robbers who swiped $1.3 million in gold, quartz and other valuable metals on display at the California State Mining and Mineral Museum in September 2012 were able to sell about $12,000 worth of gold to pawn shops and dealers, police said.

Some of the stolen items, including a bag of ground-up quartz, were recovered. Five men were convicted of the heist at the museum in the western foothills of the Sierra Nevada mountains.

The three thieves from Tuesday's robbery got away with the gold nuggets in a waiting sedan.

Wells Fargo spokesman Ruben Pulido said in a statement that the company is grateful no one was injured and no damage came to the historic stagecoaches at the museum, located at the site where Wells Fargo launched in 1852.

In addition to the stagecoach, used in the 1860s, the museum has a working telegraph and art and historical artifacts on display.

People walking to work Tuesday morning stopped to snap photos of the SUV wedged in the building's shattered revolving doors, while police surveyed the damage.

The smash-and-grab tactic has marked other recent heists in San Francisco, including at a Patagonia store near Fisherman's Wharf last week when robbers backed a U-Haul van into the building, loaded it with high-end outdoor clothing and gear, and sped off.