Police are appealing for witnesses after the incident yesterday on the B3006 Selbourne Road, Alton, at around 8.30pm.
The force said the crash happened after a red Vauxhall Corsa ‘lost control and left the carriageway, before being in a collision with a white Volkswagen Caddy van’.
Two 18-year-old men and a 17-year-old girl were taken to hospital to be treated for ‘serious and possibly life-threatening injuries’, police said.
The driver of the Corsa, an 18-year-old man, was also taken to hospital to be treated for his injuries which are not considered serious.
The driver of the van, a 26-year-old man, sustained minor injuries.
A police spokesman added: ‘Officers have conducted a number of enquiries and are now turning to the public for any information that may assist the investigation.
‘Were you on the road at the time? Perhaps you have dash cam footage showing the moments leading up to the collision?’
Call 101 with reference 44210471336.