Later reports state that the driver of the tractor was arrested on suspicion "of endangering lives on the railway"
One person taken to hospital by air ambulance, and another by land ambulance, many others treated at the scene for minor injuries.
The train remained on the track and does not look badly damaged. Probably driveable under its own power, at very low speed to a depot for repairs.
The tractor looks still useable. the trailer is substantially destroyed

Rant time.

A major problem at farm crossings all around the UK^▸ (United Kingdom). Too many farmers ignore the safety rules by either leaving gates open, not seeking permission to cross or not confirming afterwards that the gates are closed and the crossing is clear for a train to proceed. And if any livestock is killed on the track it's always the fault of the railway, not the impatient farmer who didn't close the gate(s).

Hopefully this farmer is convicted.

Rant over.

Thankfully very few injuries. The worse case scenario, one train derails and is struck by another train.

Bit presumptive that. Investigations need to carried out, parties involved to be questioned, witness statements to be gathered. Rather too early to blaming any one individual.