The staff of Japan's Fukushima nuclear power plant has been evacuated as a fire broke out in it early Wednesday, and amidst rising fears that will start emitting large amounts of radiation.

The last remaining crew at the Fukushima Daiichi NPP was pulled out at least temporarily because radiation readings from troubles throughout the plant spiked very high, Chief Cabinet Secretary Yukio Edano said at a press conference Wednesday, as cited by international media.

International nuclear energy experts have commented that the evacuation of the staff signifies that the authorities are giving up their attempts to prevent a nuclear disaster, and are focusing their attention on the next step – reacting to a possible spewing of radiation.

Three nuclear facilities in Japan were badly affected by the devastating 9.0-earthquake and the ensuing tsunami on Friday but the Fukushima NPP was damaged the most. In the past five days, the plant saw four explosions and two fires, the last one raging early Wednesday.

The last explosion in its unit 2 is believed to have probably damaged the main protective shield around the uranium-filled core inside one of the plant's six reactors. If this proves to be the case, this breach would be the first one since the Chernobyl catastrophe 25 years ago in the former Soviet Union.

The blast at unit 2 was not outwardly visible, but potentially more dangerous because it may have created an escape route for radioactive material bottled up inside the thick steel-and-concrete reactor tube. Radiation-laced steam is probably building between that tube and the building that houses it, experts said, as cited by The Washington Post, triggering fears that the pressure would blow apart the structure, emitting radiation from the core.

The cause of Wednesday's blaze at the Unit 4 reactor - also the scene of a fire the day before - was not immediately known. The plant's operator, Tokyo Electric Power Co., known as TEPCO, said radiation levels were too high for firefighters to get close, as cited by The LA Times.

Later, authorities said the blaze seemed to be subsiding on its own, as the one the previous day did. But hours later, public broadcaster NHK showed breaking aerial footage of a plume of white smoke rising from the reactor.

The earthquake and tsunami knocked out power to the cooling systems, triggering a series of breakdowns and missteps that exposed fuel rods to the air at one reactor and released dangerous levels of radiation outside the plant.

TEPCO company said an estimated 70% of the fuel rods had been damaged at the Unit 1 reactor and 33% at the Unit 2 reactor. Nuclear safety agency spokesman Shigekatsu Omukai said the utility reported the figures to the agency Wednesday.

Spent fuel at the complex is an increasing focus of concern. Tepco had moved all of the rods from the Unit 4 reactor to the spent-fuel pool sometime after Dec. 1 as part of routine maintenance, meaning the pool contained not only all of the rods accumulated from many years of service but also all of those currently in use.

If the pool was jam-packed with rods, they would generate significant heat and, once the water stopped circulating after the tsunami, its temperature would begin rising, eventually reaching the boiling point. If the water boiled long enough without being replenished, it would expose the rods to the air.