The deadly incident took place on the A303 Andover bypass, to the east of the town, at 8.40am. According to Hampshire Live a Vauxhall Astra, heavy good vehicle (HGV), DAF recovery truck and Mercedes food delivery van were all caught up in the crash.
An ambulance, police cars and a critical care car from the Hampshire and Isle of Wight Air Ambulance rushed to the incident.
The three fatalities, who were in separate vehicles, were all pronounced dead at the scene.
Specially trained police officers have been supporting their families.
After the crash the road was closed in both directions, between the A309 and A3057.
Police are appealing for anyone who saw the accident to come forward.
DC Cate Paling, the senior investigating officer, commented: “We are keen to speak with anyone who witnessed the collision, or the moments leading up to it, particularly anyone with dashcam footage.
“In the immediate moments after the collision, a small white car with a black roof passed the scene and we believe they may be an important witness who we wish to speak with.
“Anyone who can assist our enquiries should call 101, quoting the reference 44210338980.”
“We sent to the scene three ambulance officers, an ambulance crew and the Critical Care Car from the Hampshire and Isle of Wight Air Ambulance.”
Following the accident there was considerable transport disruption.
The National Highways: South West tweeted: “The #A303 is currently closed both directions between the #A3093 and #A3057 due to a serious collision.”
In response Jonathan Slayton, who was delayed by the incident, tweeted: “Avoid much of Andover – diversion right through the town – almost stationary currently”.
Traffic monitoring site INRIX warned of disruption around the Andover area.
Police also closed Winchester Road, which connects Andover to the village of Wherwell.
They said this was because “this route is unsuitable for HGVs and this has caused a number of issues”.