(CNN) Several Lululemon stores in the San Francisco Bay area have been robbed in the last two weeks, and police suspect a gang of female thieves has stolen yoga pants worth tens of thousands of dollars.

"They walk into the store, a group of two or three come in with bags and they start filling those bags with items," Officer Byron White of the Berkeley Police Department told CNN affiliate KGO.

Thieves at a Berkeley Lululemon store cleared shelves of merchandise in a matter of seconds on July 20. Surveillance video from that day showed three suspects entering the store, walking directly to the clothes and swiftly filling their bags with the high-end athletic wear.

"They are in and out. It happens in about a minute. They get into a waiting vehicle," White told CNN.

The lone store in Berkeley was also hit by thieves on July 11, 16 and 18, with two or three people entering between 1 and 4 p.m. No one was hurt in any of the incidents.

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