Any Pilots Out There?

I live North of Beale AFB and Sac Exec airport.

Last night, I saw in the distance what looked like a large plane with all red bright lights flashing.

Just now, a large plane flying fairly low, slow and quiet was also with red wing light, but bright red large light flashing under its belly.

Bith these planes were coming from north direction heading south to one of the two above destinations (my guess)

Do they use those light like that if they are having some kind of malfunction and needing to come in priority?

Always wanted to know about what the different light displays meant.

Don't normally see the all reds type, though.