Police are worried about the health of a Ngaruawahia man who's been missing since Wednesday.

The driver of a car which hit a pedestrian in the Waikato on Tuesday night was not to blame for the man's death, police say.

A police officer knocked unconscious at a call-out last night has barely any memory of the attack, say police.

Three teenage boys were arrested last night in relation to a pack attack which left two police officers seriously injured.