NEW YORK -- New York City fire officials say a fire in Trump Tower's heating and air conditioning system injured three people and caused smoke to billow from the roof. The Fire Department of New York says the fire started around 7 a.m. Monday at the building that contains President Trump's home and business offices.

The fire department said on Twitter that two civilians and a firefighter were treated for injuries that weren't considered to be life-threatening. Manhattan Borough Commander Roger Sakowich earlier told reporters some debris fell on the firefighter and an engineer breathed in some smoke.

Injury update: #FDNY confirms 3 total injuries at fire earlier this morning at 721 5th Ave, Trump Tower: 2 civilians with non-life-threatening injuries, both were treated on scene and refused further medical aid. 1 Firefighter with non-life-threatening injury — FDNY (@FDNY) January 8, 2018

It took about an hour to put out the fire on Fifth Avenue in Manhattan. Aerial views showed firefighters on the roof, with smoke billowing from one corner of the high-rise.

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The president was not at Trump Tower at the time of the fire. He left the White House on Monday afternoon to speak at the American Farm Bureau Federation's annual convention in Nashville, Tennessee, and then attend the College Football Playoff National Championship in Atlanta.

The president's son Eric tweeted his thanks to firefighters for doing "an incredible job."

"The New York Fire Department was here within minutes and did an incredible job," the younger Trump said on Twitter. "The men and women of the #FDNY are true heroes and deserve our most sincere thanks and praise!"

There was a small electrical fire in a cooling tower on the roof of Trump Tower. The New York Fire Department was here within minutes and did an incredible job. The men and women of the #FDNY are true heroes and deserve our most sincere thanks and praise! https://t.co/xuTmq1GBbj — Eric Trump (@EricTrump) January 8, 2018

People posted video and images to social media showing smoke rising from the building.

Trump Tower is on fire pic.twitter.com/qwUTAuBsEW — NYCBMD (@NycBmd) January 8, 2018

Trump tower on fire pic.twitter.com/mQgvpapw5U — Andy Constan (@constanandy) January 8, 2018

Trump tower on fire! pic.twitter.com/lUnpkc219J — Susan D. Ball (@SusanSball4) January 8, 2018

Mr. Trump announced his candidacy for the presidency in 2015 at Trump Tower, his home for more than 30 years. The building also houses luxury apartments and businesses.