ST. PAUL  — The superintendent of the St. Paul public schools has apologized for a Twitter comment she made on a grand jury’s decision not to indict a Ferguson, Mo., police officer in the shooting death of an unarmed black man.

Soon after the decision was announced Monday night, Superintendent Valeria Silva tweeted that it was a “very sad day in America.” And she asked how she could explain it to her black students.

That triggered a flurry of negative reaction, including a letter from David Titus, president of the St. Paul Police Federation, who criticized her post as ignorant and irresponsible.

Silva later deleted the tweet and apologized, saying she reacted emotionally and didn’t mean to challenge the judgment of police or the grand jury.