A Southland father says he was "blindsided" when he picked up the phone last night to news his eight-year-old son had been killed.

Police flooded the small community of Otautau last night after the boy was found dead.

Police announced today they had arrested and charged a youth with murder in relation to his death.

The person charged would appear Invercargill Youth Court this afternoon.

The 8-year-old's father told the Otago Daily Times he found out his son was killed last night and was completely "blind-sided".

The news "came from nowhere", he said.

He "loved him to bits" and had fond memories of taking him hunting and fishing as he was growing up.

He had been living apart from his son for two years, but after living in the North Island had recently moved back South to be closer to him.

His son was a swimmer, rugby player and "very well liked' by his peers.

"I was proud of him."

• Youth charged with murder over death of 8-year-old Southland boy

He had heard little from police about the investigation.

He said his son had only just moved into a new house in Otautau with his mother.

Family friend Karl Jackson rang the father last night with the news of his son's death.

"He didn't know what to say last night, he just broke down...he will never be the same."

He said the family were not new to the area, but had just moved to a new house in Otautau a week ago.

The boy was gifted at arts and crafts, he said, and was a "brainy kid".

"All his mates will be in mourning... he touched every heart that he saw."

Otautau Gallery owner Pamela Hopkins said the community was "shattered".

She said when she heard sirens last night she did not believe it would be "something like this".

Otautau was a small and close community where everybody knew each other and where people felt safe.

No-one expected "something like this would happen here".

"It is heartbreaking."

"Because my gallery is in the main road, I have a lot of locals coming here and I have a good feel of [what] this little town is like.

"I'm used to see this kids walking around, riding their bikes - feeling perfectly safe.