"A major accident resulting in a radioactive leak has happened. We apologise from the bottom of our hearts," said company President Koji Kitani, bowing deeply at a news conference in Tokyo on Thursday.

On Friday morning, JCO President Kitani, foreground, knelt down on the ground to apologise in front of the residents who took shelter in a community centre at Tokai

Three workers saw a blue flash and were overcome with nausea. They were taken to hospital barely conscious and with low blood pressure. Several other colleagues are also suffering from radiation exposure.

Workers were taken a hospital at the National Institute of Radiological Sciences in Chiba.

Those closest to the plant were evacuated and given radiation checks.

Children are particularly vulnerable to radiation. They were given thorough checks.

On Friday, residents were told it was safe to go outdoors again - most chose to stay inside their houses though. The police remained cautious, too, and continued to don protective gear.

Protesters staged a demonstration at the Science and Technology Agency in Tokyo. The banner reads: "Denounce Tokaimura nuclear processing facilities and development of Japan's nuclear power plants."