An adult and child have been found dead at a house, police said.
Officers were called to the home in Church Street in Troedyrhiw, Merthyr Tydfil, at around 4.20pm, and found the two bodies, South Wales Police said.
Police have yet to confirm the age or sex of the two victims.
The area was cordoned off last night and house-to-house inquiries were under way.
Borough councillor Gareth Lewis said he found out about the incident on Twitter and added that it would be wrong to speculate on the nature of what had happened.
He said: "All we know is that a child and somebody else, perhaps a young adult, have lost their lives.
"It is a very close-knit community, the people are very nice and will help the police as much as possible with their inquiry.
"The information started to spread online, and it will have a big impact on this community and its people."
Troedyrhiw is part of an old coal mining area, which Mr Lewis described as a "typical, traditional Valleys community".