Overnight there was an explosion at one unit of one of the two Fukushima nuclear stations that have been slowly failing since the earthquake and tsunami. Earlier reports had said that in one unit, the still hot fuel rods had been exposed by falling cooling water while problems continued at Unit 2 and three other units at a nuclear station about 15 km away.  There have also been reports of releases of cesium with seriously high radioactivity being reported in the vicinity.

The video above began circulating almost immediately – but Japan’s NHK TV went quickly away from a live shot to loops of video showing the reactor complex prior to the explosion. We cannot confirm the video but the images seem to match still photos seen on sites such as the BBC which describes the event as:

Explosion at Fukushima 1 (photo: Al Jazeera English)

A massive explosion has struck a Japanese nuclear power plant after Friday’s devastating earthquake.

A huge pall of smoke was seen coming from the plant at Fukushima and several workers were injured.

Japanese officials fear a meltdown at one of the plant’s reactors after radioactive material was detected outside it.

Four workers reported in the blast were taken to a local hospital and were said to be conscious but there is no news yet about total casualties. The Prime Minister went on TV at 3:45AM Eastern time but seemed to provide minimal information according to commenters at Ustream feed.

A BBC crew trying to drive to the scene was stopped 60 kilometers away and told that it was not safe to go closer. People in the area who had not evacuated in the earlier warning were being told to stay indoors with windows closed.

Update: There are now reports of additional aftershocks in the vicinity of the Fukushima nuclear stations.

Other updates here.