A 49-year-old man died on Thursday after the two-vehicle crash in Gordonton.
Jayda, Maverick, and Ember have been missing for two and a half years, after their father Tom Phillips took them on the run.
One person has been taken to hospital in a serious condition.
The victim was transported to Waikato Hospital where they died.
Mayor Susan O'Regan said she will not put up with abusive behaviour.
Jayda, 11, Maverick, 9, and Ember, 8, have been on the run with their father Tom Phillips for two and a half years.
Councillor Andrew Bydder says he wrote it that way intentionally, to get the attention of the Waipā district mayor.
The remains were unearthed during construction on earlier this week.
Catherine - the mother of Jayda, Maverick and Ember Phillips - shared a letter claiming to be from the children's father Tom.
