The woman, who hails from San Gwann, was in the shop owned by relatives when a man, probably a foreigner, entered the shop at around 3pm and attacked her with a sledge-hammer.
The man fled the scene and was still being sought by police late last night.
The woman was taken to St Luke’s Hospital where she was certified to be suffering from serious injuries but her condition was not critical.
Magistrate Giovanni Grixti appointed various experts to assist him in the inquiry. Sliema district police are also investigating.