WORKERS at the Dartford crossing could only watch on helpless as an out-of-control lorry ploughed into safety barriers.
The driver of the truck, who has yet to be identified, died in last night's crash.
The smash closed the busy crossing to cars travelling both from and to Kent for more than eight hours as emergency services battled to clear the scene.
Four toll booths remained shut as police launched an investigation into the accident.
Witnesses have described seeing the long-vehicle veer out of control, first hitting a roadside barrier and then swerving across the busy three-lane tunnel approach.
The lorry ploughed into the booths after cannoning off barriers on either side of the motorway up to four times, it is claimed.
The driver, who is believed to have been thrown from his cab, suffered fatal injuries and was pronounced dead by emergency services at the scene.
The crash on the A282 happened at about 7.35pm. Most rush-hour traffic had cleared by that time, but it did result in traffic being diverted via the Blackwall Tunnel.
The cause of the accident remains a mystery and no other vehicles are thought to have been involved.
PC Steven Mills is appealing for witnesses or anyone with any information which may help his investigations to call him on 01622 690690.