Seven people have died after a crash on SH1, south of Picton on Sunday morning.
Police said the crash happened around 7.30am between a refrigerated goods truck and a van at Mount Pleasant.
The road will remain closed for a significant period of time while emergency services attend the scene.
Police confirmed one of those killed in the crash was a baby under the age of one.
Along with those who died, one person has critical injuries and one has serious injuries. Those injured were flown to Wellington Hospital.
All seven of those who died were travelling in the van along with the two injured.
The driver of the truck has minor injuries.
"The highway south of Picton remains closed while emergency services attend the scene, and is likely to remain closed for most of the day," police say.
"Marlborough Disaster Victim Identification (DVI) staff are at the crash scene, as are staff from the Serious Crash Unit."
Inspector Paul Borrell said a crash of this scale has a huge impact on both the community and on emergency services.
Picton Volunteer Fire Brigade officer Wayne Wytenburg posted on Facebook describing the accident as "most horrific."
"I'm lost for words to describe what our emergency services had to deal with.
"Our thoughts go out to those effected by today's events," he said.
The accident has also disrupted Interislander ferry services, with some sailings delayed this morning.
Interislander said on its website if the road into Picton remains closed some bookings this afternoon may be disrupted.
All passengers with bookings will be notified.