WMUR Channel 9 news 11PM newscast went BLACK 6 minutes before end of news, mid sentance

[John Bolduc]

I was watching Channel 9 Manchester NH last evening and at about 11:28pm
just as they were teasing into a break, the screen went gray, and later
black. A partial color bar popped up for a couple of seconds and then
disappeared.  

Night Line came on the air at 11:35pm as usually.

Does anybody know what happened?

John B
Derry