Police expect the A120 to be closed until the evening rush hour after a lorry collided with a bus carrying around 40 children.
The crash happened on the Harwich-bound A120, near Great Bromley, at about 10.10am on Monday.
A number of ambulances were called to the scene, including the hazardous area response team (HART), a rapid response vehicle and an ambulance officer.
John Woolfenden, duty locality officer at Colchester, said: “Our staff on the scene worked very well with police colleagues to ensure everyone got the help they needed, quickly. We had a lot of resources there as we needed people-power to manage the incident and tend to patients.
“There were a large number of people to manage and we had to ensure everyone was checked and got to safety.
“We took eight patients in total to Colchester General Hospital, all with non-life-threatening minor injuries. They were very lucky as it could have been considerably worse.”
Police began clearing the backlog of traffic just before 12.40pm – ahead of the road being closed for a second time to allow both vehicles to be recovered.
With the closure expected until about the evening rush hour, motorists were advised to avoid the area and plan their journeys accordingly.
Essex Police said that the road had been re-opened at 4.15pm this afternoon.
If you saw the collision, were driving in the area and have dash cam footage, or have any other information, call police on 101 quoting incident 373 of 02/07.
In a separate incident traffic was also brought to a standstill on the A12 as a tractor load of hay bales caught light between Galleywood and Howe Green.
Both carriageways were closed following the fire, which broke out just before 1pm.
The northbound carriageway reopened shortly after 2pm, with the southbound road remaining closed between the junctions for the B1007 and the A414.
A spokesperson for Essex County Fire and Rescue Service said: “Crews were called to reports of a tractor on fire in the southbound carriage of the A12, between junction 17 (Howe Green to Galleywood).
“On arrival firefighters reported that the tractor was 50% alight and was carrying hay, which was also alight.
“After extinguishing the fire crews worked with Essex Police and Highways England to ensure the scene was safe.”
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