NEW YORK, April 7 (Xinhua) -- One person was seriously injured after a fire broke out at the Trump Tower in midtown New York City on Saturday.

"#FDNY members remain on scene of a 4-alarm fire, 721 5th Ave in Manhattan. There is currently one serious injury to a civilian reported," tweeted the Fire Department New York (FDNY) Saturday evening.

"Fire at Trump Tower is out. Very confined (well built building). Firemen (and women) did a great job. THANK YOU!" responded U.S. President Donald Trump on Twitter. He has an office and a home in the building, but he was not in New York on Saturday.

Melania Trump and the couple's son, Barron Trump, were both in Washington, D.C., according to the first lady's spokeswoman, Stephanie Grisham.

The fire broke out in multiple units on the 50th floor of the tower shortly before 6 p.m. It was knocked down by 6:45 p.m., according to the FDNY.

Videos on social media showed thick, black smoke and flames rising from the building as people watched below.

At least five fire trucks were seen responding to the fire on Fifth Avenue shortly after the blaze started.

A blaze at the same Trump Tower injured three people, two civilians and a firefighter, in January. The fire started in the building's rooftop heating and air conditioning system and left smoke billowing from the roof.