Three people, including two police officers, have been shot dead and another wounded after a domestic row in Portugal, media and officials say.

The incident took place in Quinta do Conde, 30km (18 miles) south of the capital Lisbon.

A 77-year-old man is said to have opened fire after a row over a barking dog.

He reportedly tried to take his own life with a hunting rifle and was arrested and taken to hospital.

A plainclothes officer who lived in the area was shot dead as he ran to investigate the row, and a patrol officer then called to the scene was shot in the head and killed.

The third victim was reportedly the son of the plainclothes officer who was trying to help his father.

The son was seriously injured in crossfire and died of his wounds in hospital.

One neighbour told the Lusa news agency the gunman had threatened to kill a neighbour if the dog did not stop barking "but it never crossed our mind he would try to do it".