A man armed with a knife and plank of wood is being hunted by about 20 police officers in Southampton, including armed personnel.
The man earlier attacked a 45-year-old man at a property in Villiers Road, Shirley, hitting him around the head with the wood.
Police are searching the Shirley Road area and are warning members of the public not to approach the man.
He is described as white, 5ft 10in, slim and with dark, dishevelled hair.
A Hampshire Police spokesman said they believed the assault against the man was due to a "neighbourly dispute".
Officers were called to the area at 1425 BST.
An ambulance was called for the injured man but it is not yet known if he was taken to hospital.