One person is in a coma and five others have been hospitalized after participating in a clinical trial for a new drug in northwest France.
The country's Ministry of Health said in a statement Friday that the six participants had been taking part in the trial of an oral medication at a privately-licensed laboratory in Rennes.
Many media outlets have speculated the drug is a "cannabis-based painkiller," but officials didn't address that claim.
The lab reportedly informed health officials about the incident overnight. The trial has since been halted, and an investigation is now underway.