Crews are trying to clear a major accident in Bradley County involving a jack-knifed tractor trailer. 

It happened on I-75 northbound at mile marker 16. 

The Tennessee Department of Transportation says traffic is moving slow and the right lanes are blocked. Southbound lanes are not affected at this time. 

It's not clear if there are any injuries involved in the crash and the cause of the crash is being investigated. 

TDOT doesn't expect this wreck to be cleared until 6 am. 

Stay with channel 3 on this developing story.