The circumstances of the deaths are being investigated, but troopers say it appears to be a murder scene and the four people were likely in the same family.
Police are not searching for any suspects.
Spokesman Greg Shipley says police were called to the home in Mount Airy Friday afternoon by a concerned friend who had not heard from them for a few days. The caller reported seeing a body through the window.
Shipley says the four suffered trauma, but they were trying to find out how the injuries were inflicted.
Mount Airy is about 30 miles west of Baltimore.