Riseholme Road in Lincoln has been closed in both directions due to an ongoing police incident.
Drivers were told to avoid the area, as rush hour traffic backed up on surrounding routes.
People nearby reported that the closure was enforced in the early hours of the morning on Wednesday, September 29.
Sections of the roundabout were taped off.
Reports on social media that a man has been injured have not yet been verified by police.
Police also warned that the A46, between Riseholme and Carholme roundabouts, was down to one lane due to a chemical leak.
It is not clear if the two closures are linked. Reporters have contacted police for more information.
We are on scene on the A46 between Riseholme and Carholme roundabout we have had to close one lane due a chemical leak as this has made the road surface dangerous. We are waiting for @LincsCC_roads to assist. Please allow extra time if using this route. Inc 82 29/09 ^CD pic.twitter.com/uhLzNzwAUX
— Lincolnshire Police Control Room (@FCR_Lincs) September 29, 2021
The Lincolnite has contacted Lincolnshire Police, but no one was available by the time of publishing. This story will be updated as and when more details are confirmed.