"It's really hard to put my feelings into words. That last ball I didn't think I had hit hard enough to get out of the park, but it went out."
Horner became the first player to hit four home runs in a game since Mike Schmidt of the Phillies did it on April 17, 1976, against the Chicago Cubs at Wrigley Field. However, Schmidt accomplished the feat over 10 innings.
Willie Mays of the San Francisco Giants was the last player to hit four home runs in a nine-inning game, doing it on April 30, 1961, against the Milwaukee Braves in Milwaukee.
Horner had never before hit more than two homers in a game, though he had done that 18 times.
"In my wildest dreams, I would never have expected to do anything like that," Horner said. "I had a good week today.
"The home run pitches were a fastball, two breaking balls and a fastball. It's just one of those things that happens and you can't explain it.
"I certainly don't expect that to happen again any time soon."
Horner hit a three-run homer in the fifth inning and solo shots in the second and fourth off Montreal starter Andy McGaffigan. His fourth home run, in the ninth, came off reliever Jeff Reardon.
He fouled out to first base in his other at-bat, in the seventh.
Horner's first homer, leading off the second, went over the left-field fence on McGaffigan's first pitch. He laced a 2-2 pitch off McGaffigan to deep left-center with two out in the fourth.
He capped the Braves' five-run fifth with a three-run shot on a 3-2 pitch. He tied the record with two out in the ninth on Reardon's first pitch to him.
The crowd gave Horner a five-minute standing ovation after the fourth home run.