Four people were killed in the crash on State Highway 1 in Horowhenua on Tuesday afternoon, police have confirmed.
Emergency services were called to the crash near Kuku south of Levin just after 3pm on Tuesday, after a truck and van collided.
An investigation into the cause of the crash is ongoing. The next of kin of those involved had been contacted, police said in a statement.
"Police would like to hear from any witnesses that may have information that could assist our enquiries.
"In particular, we'd like to hear from anyone who was travelling on the road at that time of the crash that may have dash cam footage," the statement said.
The NZ Transport Agency (NZTA) said it would also carry out an investigation.
"Our thoughts and deepest sympathies go out to the loved ones of the people who lost their lives, and to anyone else affected by this tragic incident," Waka Kotahi NZTA said in a statement.
Anyone with information on the crash is urged to contact police on 105, quoting file number 211109/3758.
