Rumer Willis

At Demi's House

During 911 Emergency

1/27/2012 1:28 PM PST BY TMZ STAFF
0127_rumer_willis_
Rumer Willis
was at her mom's home when Demi Moore went into a semi-conscious, convulsive state.

If you listen to the 911 tape -- around the 00:54 mark -- you'll hear the caller ask, "What is the address Ru?"

What's interesting ... Demi was clearly smoking something and, we're told, inhaling nitrous oxide with her daughter right there.

Rumer, who is 23, was partying with Demi just 2 weeks ago in Hollywood.