After the tragic mass shooting in Las Vegas, which has already claimed the lives of 50 people and injured more than 400 more, Nelba Márquez-Greene, mother of Ana Márquez-Greene, a 6-year-old girl who was gunned down at Sandy Hook Elementary school in 2012, is sounding off on Twitter in a series of remarkable and heartbreaking comments that puts the blame for yet another mass shooting directly on the shoulders of Congress. xI donâÂÂt know what to say besides this is on every congressperson who said in âÂÂ13: There is simply nothing we could do.