Japan's Prime Minister Naoto Kan says the nuclear crisis at the crippled Fukushima plant is "very grave."
Kan said on Friday the police, fire department and military were "putting their lives on the line" to cool the highly radioactive fuel rods at the complex.
Officials on Friday raised the severity rating of its nuclear disaster from 4 to 5 on a 7-point international nuclear event scale.
Firefighters were dousing water on damaged reactor buildings with powerful hoses. But they have to limit their time inside the complex due to the high radiation levels.
Japanese engineers also are extending an emergency power cable to the nuclear reactor complex. A steady supply of power could enable workers at the Fukushima plant to get water pumps working again.