It’s been 20 years, but former President Bill Clinton still remembers the moment he learned that two students killed 12 of their classmates and a teacher at Columbine High School on April 20, 1999.

“I had been to that community,” Clinton said last week at his office in midtown Manhattan. “And when I first heard about it, I thought, ‘not again,’ and ‘even there.’ “

It was immediately apparent, Clinton said, that this shooting was different — even though there had been school shootings in the years prior.

“There was something about this Columbine thing that just, you knew that it had now transcended income, class, race, everything,” he said. “That we were spiraling into some sort of a culture of violence.”

For Clinton, the tragedy presented an immediate dilemma. As cable news channels broadcast live from Jefferson County’s Clement Park, near the school, and as hundreds of reporters descended on the scene, he had to decide what to say to the American people.