Johannesburg - A mortar projectile went through the roof of a house in Brakpan central, east of Johannesburg, injuring a 20-year-old woman, Gauteng police said on Sunday.
"We are investigating the origin of the mortar projectile and who shot it," Captain Kabelo Marumo said.
The projectile shot through the woman's bedroom roof on Saturday.
He said the mortar could not have gone off on its own and urged anyone with information to assist the police.
"If they wish to remain anonymous there are channels that can be followed."
Marumo could not confirm or deny whether the mortar projectile was part of the SA National Defence Force's equipment until investigations were completed.
The woman was in a critical but stable condition at a hospital in Benoni.