Twitter users are calling out the Academy of Motion Picture Arts and Sciences for failing to include non-white actors in the recently announced 2015 Oscar nominations.

All 20 nominees for this year's best acting awards are white, and many say the omissions reflect a race problem in Hollywood. The Academy last nominated an all-white acting group in 2011, and before that in 1998.

The hashtag #OscarsSoWhite trended on Twitter immediately after the nominees were announced. It has received more than 16,000 mentions so far.