Beirut, Lebanon (CNN) — Over the past month, video has emerged from the Syrian city of Homs showing killings and other atrocities apparently committed by security forces in neighborhoods that have opposed the government.

CNN has obtained footage that is among the most disturbing yet — about a dozen family members killed in one house in what appears to be sectarian brutality.

CNN is confident of the video’s provenance. The images show a group of nine men crouched as they move across rooftops, then crawl through a hole smashed in a wall to reach a house on a sectarian fault line that runs through Homs. . .