FUKUSHIMA, Japan – Gray smoke rose from two reactor units Monday, temporarily stalling critical work to reconnect power lines and restore cooling systems to stabilize Japan's radiation-leaking nuclear complex.

Workers are racing to bring the nuclear plant under control, but the process is proceeding in fits and starts, stalled by incidents like the smoke and by the need to work methodically to make sure wiring, pumps and other machinery can be safely switched on.

"Our crisis is still going on. Our crisis is with the nuclear plants. We are doing everything we can to bring this to an end," Gov. Yuhei Sato of Fukushima prefecture, where the plant is located, told the more than 1,000 people moved away from the plant into a gymnasium. "Don't give up. We know you are suffering."

"Please get us out of here," yelled Harunobu Suzuki, a 63-year-old truck driver.

What caused the smoke to billow first from Unit 3 at the Fukushima Dai-ichi plant and later from Unit 2 is under investigation, nuclear safety agency officials said. Still, in the days since the March 11 earthquake and tsunami wrecked the plant's cooling systems, both reactors have overheated and seen explosions. Workers were evacuated from the area to buildings nearby, though radiation levels remained steady, the officials said.

Problems set off by the disasters have ranged far beyond the devastated northeast coast and the wrecked nuclear plant, handing the government what it has called Japan's worst crisis since World War II. Rebuilding the ruined northeast coast may cost as much as $235 billion. Police estimate the death toll will surpass 18,000.

Traces of radiation are tainting vegetables and some water supplies, although in amounts the government and health experts say do not pose a risk to human health in the short-term. China, Japan's biggest trading partner, ordered testing of Japanese food imports for radiation contamination.

"Please do not overreact, and act calmly," said Chief Cabinet spokesman Yukio Edano in the government's latest appeal to ease public concerns. "Even if you eat contaminated vegetables several times, it will not harm your health at all."

Edano said Fukushima's operator, Tokyo Electric Power Co., would compensate farmers affected by bans on the sale of raw milk, spinach and canola.

The troubles at Fukushima have in some ways overshadowed the natural catastrophe, threatening a wider disaster if the plant spews more concentrated forms of radiation than it has so far.