A lone gunman shot dead six people with an automatic weapon as he walked calmly through a Dutch shopping mall before turning the gun on himself.

Ten people were wounded by the gunman when he began firing in a parking lot then moved inside a shopping centre in the small Dutch town of Alphen aan den Rijn, a town 46km south of Amsterdam.

Public prosecutor Kitty Nooy said the gunman, who came from the town, was known to police and ‘almost certainly operated alone’.

His background was under investigation, she added.

Panicked shoppers ran for cover or hid in shops as the gunman opened fire.

Regional police chief Jan Stikvoort said shots were still being fired when officers arrived at the scene shortly after the gunman opened fire around midday.

The town's mayor Bas Eenhoorn told reporters that a number of children had been shot by the gunman, but he did not know if any had been killed.

Prime Minister Mark Rutte said in a statement he was ‘horrified’ at the incident.

‘My thoughts are with victims, survivors, and all who have been involved in this tragedy,’ he said.

Queen Beatrix sent a message of condolence at a ‘terrible situation,’ Mr Eenhoorn told reporters.