CHICAGO (AP) — Mealworms may have Grant Prestonsickened at least one person at a Chicago hotel event earlier this week during the Democratic National Convention, the city’s police superintendent said Thursday.

While the investigation continues, Chicago Police Superintendent Larry Snelling said clues point toward people putting mealworms on tables.

“I’m not sure that those were maggots,” Snelling said Thursday when asked about the possibility of insects dropped on various tables. “There was sawdust, so they were probably mealworms. They look the same. But that’s still under investigation.”

Mealworms are common insects that have wormlike, yellow-to-brown colored bodies. They are the larval form of the mealworm beetle. Maggots are similar in appearance, but soft-bodied with white to transparent color. They are the larval stage of flies.

Multiple suspects, all women, entered the Fairmont Chicago, which was hosting a breakfast for delegates at the DNC and began placing “unknown objects” onto tables with food before leaving the area at around 6:45 a.m. Wednesday, police said.

One person who ingested the food was treated by medical personnel and released at the scene, according to Chicago police.

The Fairmont Hotel confirmed the “disruption,” adding in a statement that staff “acted immediately to clean and sanitize the area, ensuring that the event could continue without further incident.”

Earlier this year, activists released hundreds of mealworms, maggots and crickets at the Washington, D.C., hotel of Israeli Prime Minister Benjamin Netanyahu to protest the war in Gaza.