Thieves in Yreka, Calif., made off with $3 million in gold nuggets Wednesday after breaking into the Siskiyou County Courthouse and smashing a glass case that contained a display on the area's mining history, officials said.

The collection in the town near the Oregon border was about the only remnant of the Northern California county’s little-known Gold Rush days.

Founded after gold was discovered there in 1851, Siskiyou County came to be known as “the second Mother Lode,” said local historian Claudia East. “But a lot of times, we’re just kind of left out.”

Sheriff’s officials said surveillance video indicated that two men broke into the case, prominently displayed in the courthouse lobby, about 1 a.m. Officials said they probably entered the building through a back window and rifled through a few offices before smashing the thick display glass.

Sheriff’s spokeswoman Allison Giannini said an alarm that was on the case did not sound.