Japan's Self-Defense Force continued early Saturday to shoot water at one of the crippled reactors at the Daiichi power plant in Fukushima Prefecture, north of Tokyo, for a second day Saturday in an effort to cool down the reactor and overheating spent fuel pools.

The Tokyo Fire Department's special "hyper rescue team" also joined the SDF in spraying water to cool down the No. 3 reactor and the combined effort discharged 90 tons of water.

Efforts to cool the reactor will resume on Saturday afternoon, but were suspended following plant operator Tokyo Electric Power Co. (TEPCO), attempting to reconnect electricity to the plant by using outside power sources.

TEPCO said Saturday that reconnection of the No. 2 reactor is expected to be completed during the day, but it may take some time before cooling devices can be reactivated as a lot of damage may have been caused to electrical systems when the tsunami hit the plant following Friday's 9.0 magnitude quake that struck the region.

The utility said that at the time of the quake, the No. 1, No. 2 and No. 3 reactors at the Daiichi facility were the only ones operating and shutdown automatically as they are supposed to.

But due to lost cooling functions in the reactors some of the cores are believed to have partially melted.

The buildings housing the No. 1, No. 3 and No. 4 reactors have been severely damaged, TEPCO said and fuel pools in the reactors have been left uncovered.

In addition, the No. 2 reactor's containment vessel suffered damage to its pressure-suppression chamber, TEPCO said.

TEPCO's office in Fukushima said that following the initial cooling attempts, radiation levels fell slightly 500 meters northwest of the No. 3 reactor.

The plant's operator said that post-operation readings taken as of 2:50 p.m. on Friday stood at 3,339 microsieverts per hour, compared to 3,484 microsieverts at 1:50 p.m, before the work began.

The government has set an exclusion zone covering areas within a 20-km radius of the plant and has urged people within 20 to 30- kilometers to stay indoors.

The Nuclear and Industry Safety Agency raised the severity level of the crisis-hit reactors to 5 from 4 on an international scale Friday, the same level as the Three Mile Island accident in the United States in 1979.