Although Gaston County health officials can’t point to an exact source, they say an unsafe food-handling process at a Gastonia restaurant likely contributed to a salmonella outbreak last week.

At least 25 children out of 128 who attended a banquet Friday night at City Club of Gastonia have been diagnosed with salmonellosis, health officials said. The children ate chicken for dinner while learning etiquette as part of the Junior Assembly program, which teaches etiquette, manners and dance to children in the fifth through eighth grades.

During their investigation, health officials asked City Club workers to recreate Friday night’s food preparation, starting from when the food was delivered to the restaurant.

Officials learned that the chef had placed 4-ounce pieces of chicken on the grill until about 80 percent cooked, and then put them in the oven for approximately 30 minutes at about 350 degrees, said City Club owner Graham Bell.

The restaurant should have cooked the chicken 100 percent on the grill or in the oven, a new cautionary measure it will adopt, said Gaston health director Colleen Bridger. It’s possible the chicken might have been undercooked.

The investigation is almost complete. Several test results for salmonellosis are pending, including those of some City Club staffers, health officials said.