The world is reacting with shock and revulsion to news of a horrifying massacre in Houla, Syria,  and social media activists are using Twitter to shread the word.

Video footage below. (Warning: very graphic.)

U.S. celebrities are calling attention to the news:

WaPo has details:

Syrian forces killed dozens of civilians in a village in central Syria, opposition groups and witnesses said Saturday, amid growing questions about the effectiveness of a U.N. monitoring mission that is supposed to be observing a cease-fire. U.N. officials said that at least 32 children were among the dead.

More than 90 people were killed and many more wounded when Syrian troops loyal to the government of President Bashar al-Assad shelled the village of Taldo in the Houla area northwest of Homs for several hours late Friday, according to the opposition groups and witnesses.