Efforts to restore power into the Unit Three and Unit Four reactors of the Fukushima Number One nuclear power plant were suspended after smoke was seen rising from other reactors.

Tokyo Electric Power Company, the plant’s operator, said that white smoke was seen rising from the roof of the Unit Two reactor around 6:20 p.m. Monday.

Earlier at around 3:55 p.m. Monday, white smoke was seen rising from the roof of Unit Three reactor, but the smoke disappeared after two hours.

After the smoke was detected, the power company ordered its workers to evacuate from the reactors. The workers were laying power cables and spraying water at the time the smoke was first seen.

The power company added that radiation levels inside the plant had risen to one-thousand-932 microsieverts per hour at one time before sliding down to 422 microsieverts at around eight p.m.

So far, the plant’s operator has completed connecting power lines to the Unit One, Two, Five and Six nuclear reactors.