The bodies of two adults and two children have been found in a house in Northampton.
They were discovered in a house in Pioneer Close in Simpson Manor at about 1800 BST on Sunday.
A spokesman for Northamptonshire Police said officers had opened a major incident room and more than 30 officers were involved in the investigation.
Officers are working at the scene to establish the cause of death.
The area surrounding the house has been sealed off as a forensics team conducts a fingertip search of the road.
The children are believed to be aged 11 and 18.
All four people are understood to be of Chinese origin.
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