"They spent the night in hospital and we provided some food and drinks for them and are in regular touch with them."
A representative from the company was set to visit the injured man later today, Mr Roest said.
The company had informed its employees across the country of the incident and details of the investigation, he said.
"I think we have a relatively good idea of what happened."
A Counties Manukau DHB spokeswoman said the man remained in a critical condition today.
WorkSafe NZ and the police serious crash unit are investigating.
The incident comes just a month after Lupton Carriers employee Simon Melgren died after being crushed between two trucks at his workplace in Henderson.