A fire involving 400 tonnes of straw is causing delays on a Letchworth Garden City train line this morning.
The speed of Great Northern services between Gordon Hill and Hertford North is currently reduced because of a large fire near the tracks at a farm near Cuffley Station.
National Rail has warned passengers that trains may be cancelled or "severely delayed".
Six firefighting crews - from Potters Bar, Cheshunt, St Albans, Borehamwood and Hatfield - were called to the scene of the incident at a farm on Cattlegate Road in Northaw.
The blaze started at about 5.15am, and spread to trees, hedgerows, and an adjacent manure heap.
Farm vehicles had to be removed from the area.
Herts Fire and Rescue Service station commander for Dacorum and St Albans, Lee Slipanczewski, Tweeted that the crews are currently dampening down the area.
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