A disabled woman and her elderly mother were attacked and assaulted with a gun in an armed robbery at their farm in Rosendal, in the eastern Free State, police said on Tuesday.

A gang of seven to nine people held up a domestic worker at gunpoint and robbed her of a cellphone at around 8pm on Monday.

"They proceeded into the farm house where they found a disabled 53-year-old woman and her 77-year-old mother. They tied them up with telephone cables and proceeded ransacking the house," said Sergeant Mmako Mophiring.

The elderly woman was assaulted with a gun and sustained chest and facial injuries.

Her daughter was pistol-whipped in the face.

The robbers stole five guns and cellphones before they fled.

The women were transported to the Ficksburg hospital in a stable condition.

Further investigation led the police to an area where they caught seven suspected robbers. Five of them were men and two were women.

The two guns stolen from the farm house were recovered.

Police also found two cars that were suspected to have been stolen, as a number of registration plates were found inside.

One of the suspects tried to escape and shot at the police when they cornered him.

He was wounded during the shooting and taken to a hospital in Ficksburg.

He was under police guard.

Police believed the gang was linked to other farm attacks in the area.

They were all expected to appear in the Ficksburg Magistrate's Court on Wednesday, police said.

The police thanked farmers for assisting them with the investigation.