Four bodies, including those of two young girls, were found at a house today.
Police were called to Provost Street in the New Forest village of Fordingbridge at 11.20am.
There they discovered the body of a man, a woman and the girls, aged one and two, Hampshire Police said.
Police said a member of the public found the bodies and raised the alarm.
A cordon was set up around the scene which lies in a pretty street of terraced and semi-detached houses, some with riverside views.
Neighbours said they had heard that the man slit the throats of his partner and the two young children before taking his own life.
One local resident, who did not want to be named, said: "It's pretty horrific."
Another neighbour, who also asked to remain anonymous, said the alarm was raised after noises were heard coming from the house.
His mother walked past shortly afterwards and saw somebody outside the property "walking around in the road looking like they were going to be sick".
The neighbour said the deaths had come as a shock to the village, adding: "It's a small, close community. Everybody knows each other."
A male shop worker in Fordingbridge, who did not wish to be named, said the family had not lived in the area for long.
"They were quite new to the town, as far as I'm aware," he said.
"I have worked here for many years and I know most of the people in the town.
"I believe that it all happened in the house and the police presence is quite minimal now."