A worker was killed and three others were injured Sunday during an industrial accident at a US nuclear power plant that did not release any nuclear material, officials and operators said.

Part of a generator fell as it was being moved out of the turbine building at Entergy Operations Inc's Arkansas Nuclear One in Russellville, the company said in a statement.

"There is no danger to the public," it added.

The Arkansas Department of Health stressed that the accident, which occurred around 7:45 am (1245 GMT), took place in a "non-radiation area, and there has been no risk to public health and safety identified."

The injured workers were taken to hospital, according to Entergy.

Unit 1 of the plant is offline for refueling and Unit 2 was automatically shut down after the accident.

"Both plants are in a stable shutdown condition and there is no danger to the public," Entergy said.

The accident, in which the generator stator -- the stationary part of the system -- fell, is classified as an unusual event, the lowest of the Nuclear Regulatory Commission's four emergency classifications.

"We are deeply saddened by what has happened today," said executive vice president and chief nuclear officer Jeff Forbes.

"Our greatest sympathy is with the family and friends of the employee who lost his life, and with those who sustained injuries. I also want to express my sorrow and support to all those who work at Arkansas Nuclear One. I know this is especially hard on them."

The group, which provides electricity to 2.8 million customers in Arkansas and the neighboring states of Texas, Louisiana and Mississippi, employs around 15,000 people. It owns and operates power plants with approximately 30,000 megawatts of electric generating capacity, including more than 10,000 megawatts of nuclear power, making it a top US nuclear generator.