The attraction's owner says a small section of the outside ride deck fell into the say as work to refurbish the structure was being carried.
A limited section of concrete was being cast into the far corner of the ride deck, which is currently closed off to the public, as part of a scheme to put in a new area of concrete decking.
The pier said the aim was to ensure the wet concrete being laid would not result in undue structural movement to the existing concrete deck.
However, when that was taking place, excess vertical movement of the piles caused four bays of the existing slab to fail according to Billy Ball, the Pier's director.
He said: "This was being carried out under controlled conditions at a time when the tide was up and no one was under the Pier,"
"Site personnel were carefully monitoring the pouring of the concrete when the collapse happened, and everyone was evacuated from that particular area which is now fenced off."
He also added that similar tried and tested methods have also taken place in other areas of the attraction over the past 10 years.
In total, around 4,000 square metres of the work has been carried out.
Mr Ball continued: "As part of our ongoing commitment to ensure the Pier remains safe and serviceable, we go to extensive lengths to analyse and calculate the integrity of the existing structure before constructing any new attractions,"
"Our structural engineers are currently assessing the situation."
The area in which the collapse took place is part of the ride deck which had been set aside for the new Looping Star ride due to be opened in the spring.
Images from Clacton Pier.