A cordon has been place around both properties on Dunlin Road
A man has been arrested on suspicion of murdering a woman found dead at her home an hour after police were first called to the same street.
Officers were first called to Dunlin Road, Hemel Hempstead, and "spoke with" a man seen acting suspiciously at 22:30 BST on Monday.
The 37-year-old's body was discovered an hour later, while police responded to a break-in at a neighbour's house.
Hertfordshire Police has referred itself to the police watchdog.
The force said it received the first call at 22:30 BST, and returned an hour later after a separate call about a break-in at a neighbour's house.
While they were in the neighbouring property, they heard a disturbance next door and found a woman's body, police said.
Two children were in the house when the woman's body was found, the force said, but they were physically unharmed.
A 25-year-old man was arrested soon after the woman was found dead, followed by the arrest of a 19-year-old man on suspicion of conspiracy to burgle.
Both men are in police custody.
Det Ch Insp Jerome Kent said: "This is an extremely shocking murder in which a young mother has lost her life.
Both homes in Dunlin Road are cordoned off while investigations take place.
