(CNN) Los Angeles Fire Department paramedics treated 10 people aboard the Norwegian Joy cruise ship for minor medical complaints after the ship docked early Sunday, the LAFD said.

It's the second time in a week passengers were treated for illness after returning from a trip aboard the vessel.

The patients, on a Mexican Riviera cruise, had minor medical complaints and none were transported to hospitals, the LAFD said about Sunday's incident. It was not immediately clear what caused their illness.

Initially, the LAFD was expecting to treat 20 patients "reporting unspecified illness" as the cruise ship began to dock, it said. The ship is capable of carrying more than 3,600 guests, according to Norwegian Cruise Line.

"During Norwegian Joy's Mexican Riviera sailing, a few guests on board experienced a stomach-related illness," the cruise line said in a statement. "To mitigate any impact of this rare occurrence, we implemented stringent sanitation procedures. As always, we will continue to monitor this situation."

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