Police say it wasn't the apple juice that sickened two children at an East Lampeter Township restaurant last week.

But the caustic substance they ingested remains a mystery.

Tests conducted as part of an investigation revealed today that the store-bought apple juice was not contaminated by the manufacturer or before it was purchased by Star Buffet & Grill on Lincoln Highway East.

"We have no evidence thus far that the juice itself was the cause of the injuries," police Lt. Robin Weaver said.

The findings do not provide any clarity on how the children became ill or who is responsible. But they seem to clear the juice manufacturer and suggest the unidentified substance that made the children sick was either introduced into the apple juice after it was poured from the container or ingested separately from the beverage.

"There is no evidence that there is any further danger to the public," Weaver said. "If a local or state agency had an issue with a brand, it would have been publicized."

Ten-year-old Richie Zaragoza and his 4-year-old half-sister Ginaya Mercado suffered severe burns to their throats and mouths after drinking cups of the apple juice they ordered at the restaurant last Friday.

The Department of Agriculture has been testing samples of the substance since late Monday, spokeswoman Shannon Powers said. Results of the tests were provided to the East Lampeter Township police department today, Powers said.

She declined to comment on the results, citing the ongoing police investigation. Police said they received initial results, but the testing is not complete.

"We're still looking for the cause," Weaver said. "The information received so far doesn't change or affect the direction of the investigation. All possibilities are still open."

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"Releasing the results could effect the investigation," he said.

The father of Richie, Richard Zaragoza Sr., previously told LNP that a test from Hershey Medical Center revealed that methanol was at least one of the substances in the juice.

Restaurant manager Steve Weng told LNP the juice came from a local supermarket and was served from a half-gallon jug into foam cups.

Related: East Lampeter police investigate if incident of children drinking caustic substance at restaurant was criminal or accidental

After the incident, the children were airlifted to Penn State Hershey Medical Center where they have been since. A hospital spokesperson said they were in good condition Friday. Police said that a 6-year-old and an adult male were also briefly hospitalized after drinking the juice.

Related: Lancaster County, state, federal agencies investigate incident of children drinking caustic substance at restaurant

The restaurant, at 2232 Lincoln Highway East, was inspected by the Department of Agriculture and allowed to remain open Monday. But it was closed Tuesday by township officials after it failed a building code inspection by a zoning and codes officer.

The Department of Agriculture has the power to shut a food facility down if it's deemed an imminent health risk, Powers said. But an inspection report released Tuesday listed 11 violations. It also said the inspector found several bottles of crystal lye. One was stored inside a sushi buffet area.

The inspector took a box of three bottles of the lye for the laboratory, the report said.

"It's rare for our inspectors to see lye," Powers said. "It is used as a drain cleaner, but it is rare for us to see it in a restaurant."