Traces of cresol solution were found Wednesday afternoon in containers used to help two longtime patients intake liquid food at Yamanashi Red Cross Hospital in Kawaguchiko, Yamanashi Prefecture, suggesting foul play, police said Thursday.

The two patients are doing well in an intensive care unit after their stomachs were pumped by the hospital, along with 15 other patients who were also receiving about 600 ml of nutriments via feeding tubes.

The two, a 74-year-old man and a 69-year-old woman, had received about one-third and two-thirds of the liquid contaminated with the disinfectant agent, respectively, when a nurse noticed a change of color in the plastic containers around 5:15 p.m.

According to sources close to the investigation, three hospital staffers were involved with the patients during the period of roughly 85 minutes from when the liquid nutrients were placed in the plastic containers and distributed to hospital rooms until the discoloration was discovered.