January 15, 2016 8:15 AM EST

A drug trial for an unnamed pharmaceutical firm in France has left one person brain dead and five others critically ill.

The six patients were in good health until taking the oral medication in Rennes, north-west France, wrote the French Health Minister Marisol Touraine in a statement according to AFP.

She said on Friday that “a serious accident took place,” which has resulted in the study being halted and all volunteers taking part recalled.

According to the Guardian, Touraine also said that the patients were admitted to hospital at the beginning of this week and six people had taken part in the trial that was being developed by a European laboratory .

While the intended use for the new medicine is unknown, a source told AFP that the drug was a painkiller containing an active ingredient found in cannabis plants, cannabinoids.

The French state prosecutor has opened an inquiry and all trials on the unnamed drug in the clinic has been suspended.




Contact us at letters@time.com.

Read More From TIME

Related Stories