Police have a issued a warning after officers said they believed three people found unconscious outside a pub had taken a dangerous chemical.
Two women and a man were taken to hospital after they were found in the street outside the Zetland pub in Marske High Street, Cleveland. One of the women remains in a critical condition.
Cleveland Police said they were discovered at 12.35am and taken to the James Cook University Hospital, Middlesbrough.
Paramedics found the 22-year-old man had minor external injuries but the women - aged 27 and 22 - had no visible sign of being hurt.
Detectives now believe they have all ingested a chemical, possibly gamma-butyrolactone.
This substance - sometimes known as GBL - is an industrial solvent which is similar in its effects to the better known, and now banned, GHB.
A force spokesman said: "The 27-year-old woman and the 22-year-old man have regained consciousness this morning, whilst the 22-year-old woman remains in a critical condition in hospital.
"Officers have issued a warning to people not to take dangerous chemicals as their effects can be extremely harmful or even fatal."
Anyone with information has been urged to contact Detective Inspector Mark Dimelow on 01642 302626.