The crash happened on London Road near the Stonehouse Corner roundabout around 10.15pm yesterday (April 24).
A 17-year-old boy died at the scene and an 18-year-old man from Rainham was arrested on suspicion of causing death by dangerous driving and is in custody.
The road was shut overnight but is now open again.
An Essex Police spokesman said: “We are now appealing for any drivers in the area at the time of the collision to get in touch, in particular with dashcam footage, to support our enquiries.
“You can let us know by submitting a report on our website or by using our online Live Chat service which is available 24 hours-a-day, seven days-a-week.
“It can be found at the bottom right of our homepage at www.essex.police.uk.
“Visit www.essex.police.uk/digital101 to find out more about our website reporting services.
“Alternatively, you can call us on 101. In an emergency always call 999.
“If you would like to make an anonymous report you can contact independent charity Crimestoppers, by visiting their website or by calling 0800 555 111.”
