At least 81 people fell ill from suspected salmonella poisoning after eating guinea pig meat and other foods from a vendor at a Minneapolis street festival earlier this month, health officials said.

The vendor had a city permit but sold unapproved food and handled it improperly, according to a city spokesman.

The outbreak happened at the Ecuadorean Independence Day celebration at the New York Plaza Produce grocery, 1304 E. Lake St., on Aug. 11. Scores of people went to Hennepin County Medical Center and Children’s Hospital of Minneapolis with severe gastrointestinal symptoms after eating the tainted food.

Bill Belknap, a spokesman for Hennepin County Public Health, said some of those who fell ill ate a traditional Ecuadorean dish that contained guinea pig, but others who didn’t eat that dish also were sickened. The Minnesota Department of Health said a number of them tested positive for salmonella. Everyone who fell ill was treated and released.

“It was most likely a bad food item or items being poorly handled,” Belknap said. “The diseased organism that originated somewhere got spread to other food items by cross-contamination.”

The city had issued separate permits to Nieves Riera to put on the festival and serve food, said Matt Laible, a city spokesman.

Laible said Riera “did not follow the rules that applied to the permit. The vendor sold food it was not approved to sell, and used preparation practices that were not approved by the health code.”

The Minnesota Department of Agriculture, which licenses the grocery, took samples of several food products sold at the festival and is testing them to pinpoint the cause of the contamination, said Margaret Hart, a spokeswoman for the department.

Jorge Alvarado, the owner of a company affiliated with New York Plaza Produce, declined to comment, noting the current investigation. Riera could not be reached.