The zoo confirmed a short time ago that a blaze had broken out in its Monsoon World habitat.
They said visitors have been evacuated and the zoo's response team were working alongside emergency services to bring the situation under control.
The added the zoo was now closed and further updates would provided as soon as they have them.
Videos shared on Twitter show huge plumes of smoke billowing from the top of a domed building.
Chester zoo boast they are the the largest indoor zoo exhibit in UK history, with thousands of tropical animals and plants on display.
The Monsoon World habitat where the fire has broken out is home to crocodiles. monkeys and exotic birds.