This post is obsolete. It was a developing live-blog of events and is no longer accurate.
A compilation from various sources:
- Massive (8.9) earthquake struck off Japan coast
- 11 reactors automatically shut down 
- Emergency declared at Fukushima Daiichi NPP after failure of reactor cooling systems 
- Specifically, backup generators failed 
- No AC power at all at Fukushima Daiichi units #1,2,3 ; running on batteries 
- "status of reactor water coolant injection could not be confirmed" for units #1,2 
- Nuclear agency says "...plant workers are currently scrambling to restore cooling water supply... no prospect for an immediate success" 
- Evacuation order issued  at a 3 km radius  
- Separately, emergency core coolant system activated  in Fukushima Daini unit #1 following suspected coolant leak 
- Separately, fire in turbine hall at Onagawa NPP 
- Separately, unspecified coolant leak at another Onagawa unit 
- No radiological releases recorded [all sources]
The NPP has 10 reactors: Fukushima Daiichi (Fukushima 1) has six units, and Fukushima Daini (Fukushima 2) has four. According to TEPCO, Fukushima Daiichi #4,5,6 were in an outage, and the other seven were shut down in the earthquake .