Emergency services were called to the scene in Alford Road at 11.10am today.
The A111 is currently closed between the junction with the A1104 at Alford, and the junction with the B1449 at Bilsby.
There are now severe delays on the roads nearby, and motorists are asked to avoid the area.
Anyone who witnessed the incident should call 101, quoting incident 121 of October 5.
No further details have been released at this time.
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