Media playback is unsupported on your device
Media captionThe victims were “targeted specifically” – Assistant Commissioner Mark Rowley
A nerve agent was used to try to murder a former Russian spy and his daughter, police have said.
Sergei and Yulia Skripal were found unconscious in Salisbury on Sunday afternoon and remain critically ill.
A police officer who was the first to attend the scene are in a serious condition in hospital, Assistant Commissioner Mark Rowley said.
Nerve agents are highly toxic chemicals that stop the nervous system working and shut down bodily functions.
They usually enter the body through the mouth or nose, but can also be absorbed through the eyes or skin.