Two men have been receiving treatment for cyanide poisoning on Lewis after an accident with a container of the chemical.
Two female paramedics which went to their aid in Uig were also treated for contamination from the poison.
A main route on the island was closed for hours while the four people were decontaminated in an open area before being admitted to hospital.
It is understood a dust cloud of cyanide powder sprayed into the air when Dickon Green of Uig Lodge in Timsgarry accidentally broke a container containing the poison which was used to kill vermin.
He feared he inhaled the poison and got it on his skin. He phoned for an ambulance but a neighbour drove Mr Green towards the Stornoway hospital to save time.
They met the paramedics on the way and both transferred into the ambulance which headed for hospital.
Police stopped the ambulance on a moorside location between Achmore and Cameron Terrace to prevent any further contamination of the poison in the hospital.
The main road was shut to traffic for hours as a result. An alternative route by the old single track Achomore road remained opened so no villages were cut off.
The four people were hosed down by fire crews and were treated by other paramedics.
Later, they were taken to a portable decontamination tent set up outside the Stornoway hospital.
Earlier on Thursday both ambulance personnel and the car driver were discharged following assessment.
Dickon Green is still in hospital but is due to be discharged later today.
Uig Lodge has been sealed off by police. Fire personnel are checking what rooms have been exposed to cyanide dust. Affected areas will required to be decontaminated before the property is safe.
Four in cyanide poisoning alert 25/10/12
A decontamination tent was set up at the Stornoway hospital