The couple, who have not been named, were taken to St Mary's hospital, Paddington, after the woman managed to raise the alarm. Their conditions are described as 'stable, but very ill'.
According to Scotland Yard, they were returning to the man's flat in Westbourne Terrace, Paddington, at about 6.30pm. The man, who underwent surgery yesterday morning, was shot four times in the head and back when he and the woman stepped out of a lift into a communal hallway. The woman was shot once in the mouth, but managed to struggle to a telephone and call the police.
'Two men of Arab appearance are being sought. Both are believed to be in possession of handguns,' a Scotland Yard spokesman said.
Two handguns which detectives suspect were used in the attack were found in a nearby street.
Police are appealing for witnesses who may have seen the gunmen escape in a car from Eastbourne Terrace to telephone the incident room at Belgravia Police station on 071 321 6755.