The A134 in Tottenhill, near Downham Market, is currently closed in both directions after a lorry shed some fertiliser.
Crews from King's Lynn's fire station attended the scene just before 7am after the spillage and made the scene safe.
Police officers are currently directing traffic as recovery work continues to move the broken down lorry and remove the fertiliser.
Drivers are being advised to avoid the area if possible with long tailbacks of traffic starting to build up.
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