People who say they’ve been sickened by E. coli after eating at Chipotle Mexican Grill restaurants in Oregon and Washington have retained a high-profile, Seattle-based attorney.

So far, the bacteria have sickened 23 people, a number health officials say will grow as the investigation into the outbreak continues. Nine of those people were hospitalized.

The restaurant chain has temporarily closed 43 stores around Washington and the Portland metro area after health officials notified the company about a possible E. coli outbreak linked to the restaurant chain.