"In many ways, this is the perfect time to remember Oklahoma City and to repeat the promise we made to them in 1995 to all Americans today," Clinton wrote in an op-ed published Sunday in The Oklahoman. "We have not lost each other, we have not lost America, and we will stand together for as many tomorrows as it takes."

It was 25 years ago on Sunday that a Ryder truck filled with fuel and fertilizer exploded outside the federal building in downtown Oklahoma City . The bombing killed 168 people, including 15 children inside a day care center, and injured hundreds, which at the time made April 19, 1995 the deadliest day for a terrorist act in the US, before the attacks of September 11, 2001.

Clinton, who was in the third year of his presidency at the time, recalled that moment of historic challenge on Sunday as he reflected on the nation's current crisis.

"We face the same choice today," Clinton wrote. "The best way to honor those who perished in Oklahoma City, and those all across America lost in the current crisis, is to embrace the Oklahoma Standard: service, honor and kindness. It worked wonders before. It will again."

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