Ruling Question -- Ground rule double or homerun?

[josephgarland]

Hi everyone, I had a quick question over something that I've never seen before.

I know that when a fly ball hits off a glove or part of the player and goes over the fence that it is a homerun.

However, the other day, a ball was hit deep down the foul line at the fence, the outfielder was in FAIR territory and it hit off of his glove, but the ball went over the FOUL fence. How do you rule this?

I assumed it would be a ground rule double, but correct me if I'm wrong.

Thanks!