Emergency crews were called to the scene at about 2.30 pm following a crash involving a van and a tanker.
A police spokesman explained diversions were put in place and motorists are being advised to avoid the area until further notice.
Meanwhile, Dumfries and Galloway Council have announced the X74 Dumfries-Moffat-Glasgow bus, the 74 Dumfries to Moffat service and the 101 Dumfries-Moffat-Edinburgh bus have also been diverted as a result, from Dumfries Marchfields to the A709 Lockerbie and then on to the B7076 to Beattock.
