Moments earlier they had been told that the company was to begin to wind down operations in Ballymena from next summer.
High energy costs and a flood into European markets of cheap lorry tyres manufactured in Asia were blamed.
Halfway through next year the company will begin to remove machines from the factory at Raceview Road.
Father-of-three Damian Hegarty, an instructor who has worked for Michelin for 21 years, said: "Everything was normal until nine this morning.
"The company told staff that energy costs are a major factor in the decision, along with the competition posed by cheap imports from China," he said.
"I'm having to consider uprooting my family from Ballymena to take up Michelin's offer of redeployment in other locations across Europe."
He admitted: "I'm thinking about it."
Michael McGaughey, who has worked for Michelin for 18 years, said the decision was unexpected despite a lot of talk about the economic situation worldwide.
"Everybody felt that something could happen somewhere, but you never expect it will happen on your own doorstep. It's devastating for the community," he said.
The shock decision will have a knock-on effect for the local economy as the wages of up to 800 people will no longer be going into the system, he added.
DUP MLA Paul Frew said there was no "immediate inkling" that this was about to happen. "It has come as a massive shock, not least to the employees," he said.
The future looks increasingly bleak for Michelin as a whole, he said, with a loss of demand for lorry tyres in Europe and "crippling" competition from cheaper production in Asia.
But he added that Michelin has set aside a £5m fund to provide advice and development for employees who want to look at starting up their own business.
Martin McAuley, an employee for 21 years, said another Michelin plant in Fossano, Italy, received news yesterday morning that it was to be closed.
"They are basically going to ramp down production all across Michelin plc's European sites," he said.
"They are going to start taking the machines out in the middle of next year and they're looking to close in 2018.
"There is talk of retraining and talk of people being allowed to relocate to different sites. But it's all up in the air because nobody knows what's going on. We can't compete, really, in terms of energy costs. There are cheaper imports from China which are crippling our own markets.
"How they can produce tyres at half the price and still meet safety is beyond our control.
"It's a hell of a shock to a lot of guys who have spent the best part of a lifetime working for Michelin."
DUP MLA David McIlveen said the closure will take millions of pounds out of the local economy.
"There are so many challenges in the global markets, but I am most frustrated about the fact that the utility regulator was warned that spiralling energy costs were putting the viability of this factory more and more at risk. But it was ignored," he said.
"It's something that I believe could have been done to alleviate the pressure the company was under."
Mr McIlveen said the "absolutely devastating" announcement revived haunting memories of where Ballymena was a year ago when JTI announced it was pulling out.
"We've been watching Ballymena for some time losing its position as a private sector powerhouse - we're seeing that slipping away."
Local businessman Thomas Wallace, director of Wallace's menswear shop, said the impact will be felt well beyond Ballymena, as many workers travelled from all over Northern Ireland.
"It's a sad day for Ballymena to lose a big employer," he said. "It's bound to have an impact long-term. I hope they can go out and get some other manufacturer to take over the premises.
"As a shopping town, Ballymena is still going grand.
"There was an impact a year or two ago but things have been going well these last months and it was looking brighter until that news broke.
"The impact will be three or four years down the line. It will be an effect on Ballymena, but a lot of the workers travel from all over the province, so it will have an effect across a wider area than just the local town.
"It's bad news for the Michelin staff at this time of the year, to get that news in the mouth of Christmas. I feel very sorry for them."
Eugene Diamond runs a newsagents close to the factory and workers regularly call in to his shop.
He said: "This is a nightmare blow for Ballymena, which is still reeling from the shock last year about JTI shutting down.
"It will affect every business in Ballymena and further afield. There are people from Armoy, Ballycastle and Larne who work there. There are private contractors affected, like hauliers.
"The airline industry will be badly hit, thousands of flights will be lost and hotels too will suffer."