Published: Mar 18, 2011 6:24 PM EDT
Updated: Mar 18, 2011 3:26 PM EDT

TOKYO- Japanese authorities have raised the rating of the nuclear crisis to a Level 5 from a Level 4 on a seven-point international scale.

That puts it on par with the 1979 Three Mile Island accident in Pennsylvania. The reclassification comes as the government asks the U.S. for help and acknowledges that its response to the nuclear disaster was slow because it was overwhelmed by the earthquake and tsunami.

Military fire trucks spray overheating reactor units for a second day, while the utility that runs the plant continues to work on a new power line in an effort to restore cooling systems.

(Copyright 2011 by The Associated Press. All Rights Reserved.)