Trains from London Liverpool Street to Cambridge and Stansted Airport were hit by three-hour delays after a Greater Anglia service hit a cow.
Part of the eight-carriage train was taken out of service after it hit and killed the cow on a Cambridge-bound service between Roydon in Hertfordshire and Harlow Town in Essex, reports the Hertfordshire Mercury.
According to the Herts and Essex Observer, a replacement bus service was used to take passengers between Stansted Airport and Broxbourne.
A Greater Anglia spokesman told the BBC that trains should now be running smoothly.
London commuters delayed after train hits cow
Panic as passenger train 'hits herd of cows on track'