It happened at around 00:30 on Sunday morning.
Two of the people involved had to be taken to the Emergency Department for further treatment. Ambulance clinicians assessed another three people at the scene, however none of these needed further medical attention.
All emergency services were called to the scene, including a double crewed ambulance and a second paramedic ambulance.
Guernsey Police, Guernsey Fire & Rescue Service and Civil Protection were also in attendance. The road remained closed after the ambulance and fire services left the scene, as police officers spent hours investigating the crash site.
Forest Road was reopened around four and a half hours after the crash.