The Loud Growl

It was around 1:00 am & I was asleep, but abruptly awoken by Karen & my 2 daughters. They heard, what was a loud bear like growl, that happened twice and either came from playroom/upstairs area and/or diningroom area, they were not quite sure, but it really scared them and had them almost crying and staying close to me while I checked things out. Something new going on & that is a major something new and sounding not so good either.