Fukushima Prefecture residents expressed anxiety Monday after a power outage left three fuel storage pools without fresh cooling water for hours at the disaster-hit Fukushima No. 1 nuclear power plant.

Masahide Matsumoto, mayor of Katsurao village, which was evacuated after the outbreak of the nuclear crisis in March 2011, said the incident came at a sensitive time, as evacuation zones were set to be reclassified Friday, with some residents granted permission to make day trips to their homes.

"We will be in trouble unless Tokyo Electric Power Co. properly investigates the cause (of the outage) and restores power," Matsumoto said, citing growing concerns among residents.

A 27-year-old housewife in the city of Fukushima said, "I am very worried because I have a baby. I want the information to be disclosed as quickly as possible because it will be difficult to evacuate promptly if (an emergency occurs) at night."

The power outage occurred just before 7 p.m. and was made public by the Nuclear Regulation Authority three hours later.

Takashi Haga, a 49-year-old office worker in the city, appeared surprised by the latest incident.

"It revived the memory of the nuclear accident two years ago," Haga said. "I thought it was under control."

At the Fukushima prefectural government office, four staff members at a nuclear safety division received information from Tepco and communicated with local municipal officials. The staffers appeared relatively calm, with one of them saying, "We want Tepco to pin down the cause and respond to the situation."

Makoto Yanagida, a representative of the "Tanpoposha" (No Nukes Plaza Tokyo) antinuclear group said, "It's just nonsense that a power company is hit by a blackout. We need to be vigilant, though, to see if Tepco is going to make public what really happened."