Trump Tower was evacuated Tuesday and the NYPD and FDNY rushed to the scene to investigate — all because a little kid left behind a backpack full of toys, authorities said.

The scare unfolded about 4:30 p.m. when a “suspicious package” was reported in the building’s atrium near Nike Town.

Authorities took no chances and a bomb sniffing dog was brought in and sat on the package, suggesting it was an explosive.

But further investigation revealed there was no threat.

“All clear at Trump Tower following the earlier suspicious package in the lobby,” an NYPD spokesman announced.

Surveillance video showed that the unidentified boy, who was with his family, had left the yellow backpack behind in the building on Fifth Avenue in Midtown.

Wags took to Twitter to poke fun at what turned out to be a false alarm.

“The suspicious package at Trump Tower has been identified as a tax return and has now been destroyed,” wrote Jeremy Price. ‏

“Suspicious package reportedly shuts down Trump Tower. No word on whether it’s Trump’s package that’s suspicious,” tweeted Ana Maria Montoya.‏

“Trump Tower is being evacuated. There’s a ‘suspicious package.’ It’s probably a book,” added Damien Owens.

A video on Twitter posted by a user named Cielo showed cops waving to people inside the building to get out and crowds running toward the exits onto nearby streets that were packed with holiday shoppers.

The building is home to president-elect Donald Trump, who was in his Mar-a-Lago resort in Florida on Tuesday.