Lenexa ? Lenexa (ap) — Health officials are trying to determine what may have caused more than 20 people to become ill at a Lenexa restaurant.

Twelve of 22 people who complained about illness Sunday night at the Mi Ranchito restaurant were taken to hospitals.

Dirk Fetterolf, EMS battalion chief for Johnson County Med-Act, says the customers complained of nausea, vomiting and dizziness. It was the second time in less than a month that people at the Mi Ranchito restaurant became ill.

Restaurant officials said the diners suffered carbonic acid poisoning caused by faulty water lines. But state officials said not all those who got ill had carbonated drinks, and preliminary testing has not confirmed that was the cause.