INDIANAPOLIS — More than 300 people say they became ill, and at least three have been hospitalized, after eating at an Olive Garden restaurant last weekend, health officials said Friday.

The restaurant has been closed while health officials and the company investigate what caused customers to complain of nausea, vomiting, fever and diarrhea, a company spokesman said.

Steve Coe, a spokesman for the Orlando, Fla.-based chain of Italian restaurants, said health officials are focusing on an employee who had flu-like symptoms similar to those patrons complained of.

Six restaurant workers reported Monday that they felt ill, said Marion County Health Department spokesman John Althardt.

“We’re trying to isolate what the cause of the illness might be,” he said.

Health officials have found no link to the E. coli outbreak that sickened dozens of people who ate at Taco Bell restaurants in the Northeast recently, Althardt said.

The reports have been isolated to the one restaurant, appearing to indicate the problem is not linked to any products used in the food, Coe said. Food suppliers typically supply the same products to many restaurants.

“We are taking this extremely seriously,” he said. “But at this time there is no reason for us to believe that there is any connection with any E. coli outbreaks.”

Health officials were collecting leftover food and stool samples from those stricken to pinpoint the source, Althardt said. Inspectors met with restaurant managers on Tuesday and found no health code violations.