ALPHEN AAN DEN RIJN, Netherlands  - A gunman's deadly rampage through a shopping mall was met on Sunday with disbelief by residents of a quiet Dutch town who once thought such carnage could not happen in their country.

Dressed in camouflage trousers and a bomber jacket, Tristan van der Vlis opened fire with an automatic weapon in a parking lot on Saturday and walked calmly into Ridderhof mall, where he continued shooting.

Six people died, including a woman of 91 and an 80-year-old man, and 17 were wounded, including two children aged six and 10-years-old.

The 24-year-old gun club member then shot and killed himself.

"This is something you usually see in America, not in the Netherlands," said local resident Martin van der Ploeg as he fixed his motorbike near the mall.

The town of Alphen aan den Rijn, 46 km (29 miles) south of Amsterdam, lies between the university cities of Leiden and Utrecht, and is close to the area of the Netherlands famous for growing tulips and other bulbs.

"Dutch people consider themselves down to earth. We don't have this sort of excess," Van der Ploeg said.

"This was my home, my sanctuary, where I need to feel safe, and now that's gone."

The shooting spree was the deadliest attack in the Netherlands since a Dutch national drove his car into a crowd in 2009, killing seven people and himself in an apparent attempt to hit the queen in Apeldoorn, 90 km (55 miles) east of Amsterdam.

NO MOTIVE

The gunman left a farewell letter, found by his mother, in which he mostly talked about his suicidal feelings. He lived in a nine-storey building some 200 metres (yards) from the shopping mall.

"He was very polite and very nice," said one of Van der Vlis's neighbours, a woman who declined to be identified.

"I was very surprised to hear it was him who shot. I have kids and often they were in the elevator with him, and now when I think about it, that is scary," she said.

Public prosecutor Kitty Nooy said after questioning members of Van der Vlis' family, investigators had still found no motive for the attack.

"This young man had psychological problems and that was known by a certain number of people," she said.

Nooy said previously that Van der Vlis had acted alone and was investigated by police in 2003 on suspicion of violating weapons laws but not convicted. He had a licence for five guns and owned three.

Nooy told reporters on Sunday three guns had been found and it was not clear whether one of the guns had been upgraded. As a member of a shooting club, Van der Vlis was allowed to keep a semi-automatic weapon at home, but should not have had access to automatic weapons, investigators said.

The shooting has prompted calls for an investigation into the Netherlands' gun laws.

"It is not up on us to change the policy, we will leave it for (the government in) The Hague to do it. We are not going to comment on that further," said Bas Eenhoorn, the town's mayor.

INCOMPREHENSIBLE

Messages of condolence have poured in from members of the public, expressing shock such an incident could take place in a country with no history of random killings and a reputation for a relatively low crime rate.

"Incomprehensible. It is so incomprehensible that all words fail," said a message on the public condolence page signed "Anita".

On Sunday, several police stood outside the cordoned-off shopping mall, while people were out on the quiet streets, walking their dogs or cycling.

Frank Oppelaar, who lives next to the mall, said he thought the noise he heard as Van der Vlis shot his victims sounded like fireworks.

"I thought it was a little early for fireworks. I went out on my balcony and took pictures of people running in panic from the shopping mall. It's terrible what has happened," he said.

The gunman left a second letter in his car in which he said there were explosives in three other shopping malls in the town, police said.

Authorities evacuated the buildings but so far no explosives have been found.