A Port Elizabeth man suffering from stage four lung cancer  shot  dead his daughter before turning the gun on himself.

The murder-suicide happened in Fifth Avenue, Newton Park, about 11pm on Sunday.

Johannes Maritz, 74,  shot his daughter Merisa,  47, in her bedroom.

Police spokesperson Capt Sandra Janse van Rensburg said Johannes’s younger daughter, 46, who police are not naming,  was visiting from Moorreesburg in the Western Cape and was in the house at the time of the shooting.

“They all went to bed and it appears that shortly before 11pm, the [younger] daughter heard movement in the house.

“After a while, she became suspicious and went to investigate,” Janse van Rensburg said.

Officers on the scene said Johannes shot Merisa in the bedroom, prompting the other daughter to run to her bedroom to call for help.

“She heard a second gunshot and found her father in the bathroom later, where he had shot himself,” Janse van Rensburg said.

According to police, the firearm was registered to Johannes.

Janse van Rensburg said an inquest and a murder investigation were  under way.