El Pollo Loco is tanking after earnings

Shares of El Pollo Loco tanked by more than 11% in after-hours trading on Thursday after the company reported weaker-than-expected comparable store sales.

The restaurant chain posted first-quarter earnings per diluted share of $0.18, just above the forecast of $0.17 , according to Bloomberg.

The company posted revenues of $90.4 million, up 11.1% year-over-year, and beating expectations for $88.5 million.

But its comparable store sales, at restaurants open for 15 months or longer, grew 5.1%, lower than the 5.7% that was expected.

"We are very pleased with our first quarter results, which once again demonstrate strong operating momentum through solid sales and earnings growth," CEO Steve Sather said in the statement. "Our Crazy You Can Taste authentic Mexican inspired cuisine continues to resonate with guests, as evidenced by our system-wide comparable restaurant sales growth of 5.1%, which extended our track record to 15 consecutive quarters of positive comparable restaurant sales growth."

The company forecasts diluted earnings per share of between $0.67 and $0.71 in 2015. It expects to open 16 company-owned and 11 franchise-owned restaurants this year.

Investors have said the company could be the next Chipotle.

Year-to-date, the stock was up 45% excluding the after hours sell off on Thursday.