The A16 in Boston outside Pilgrim Hospital has been closed by police.
Officers are advising motorists to avoid the area and a diversion is being put in place.
Lincolnshire Police tweeted initial details of the accident at 9.05 and posted an update at around 10.30.
The update said: "The A16 Sibsey Road, Boston has been closed outside of Pilgrim Hospital due to an RTC.
"Anyone needing to get to the hospital can still get access but we are asking other motorists to avoid the area. We will update with further details when we can."
There are no details of injuries or vehicles involved at the moment.
Anyone who may have information or who witnessed the accident is asked to call 101 quoting incident 104 30/05/2019.