90-Year-Old Nancy Reagan Takes a BIG Spill

8/24/2011 9:45 AM PDT BY TMZ STAFF

Former First Lady Nancy Reagan took a nasty fall last night at an event in California -- but thankfully, a nearby Senator caught her mid-fall ... INCHES before the 90-year-old would have slammed to the ground.

Nancy was being escorted to her seat at the Ronald Reagan Presidential Library in Simi Valley, CA  when she took the plunge, but the man escorting her -- Senator Marco Rubio (R-Florida) -- caught her just in time.

A spokeswoman for the library claims Nancy was NOT injured.