WATCH: Crowd At Paris Unity Rally Sings John Lennon's 'Imagine'

In 1980, John Lennon explained the meaning behind his song “Imagine.” Speaking with Playboy reporter David Sheff, the former Beatle said, “‘Imagine’ is saying that [if] you can imagine a world at peace … then it can be true.”

More than three decades later, Lennon’s song unified a crowd at a Paris rally this Sunday, held in the days after extremist attacks claimed the lives of 17 people. The crowd, participating in a national unity march that saw millions around the country flooding the streets to show their support, raised their voices as one to sing along to the inspiring song.

YouTuber Lâm Hua wrote that his neighbor decided to open the windows of her home, located near the Paris march, to play music for the crowd gathered. When “Imagine” came on, many attendees spontaneously joined in -- singing, clapping and cheering.

“You may say I'm a dreamer, but I'm not the only one,” the crowd sang. “I hope someday you'll join us, and the world will live as one.”

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(Watch the uplifting video above.)

Last Wednesday, brothers Said and Cherif Kouachi are suspected of storming the Paris newsroom of satirical magazine Charlie Hebdo, killing 12 people. In the two days that followed, a man named Amedy Coulibaly, believed to have ties with Cherif Kouachi, is suspected of killing a policewoman on the outskirts of Paris and four people inside a kosher grocery store. Coulibaly and both Kouachi brothers were killed by French police Jan. 9.

At the government-sponsored rally on Sunday, French Prime Minister Manuel Valls called for French unity in the wake of the national tragedy. “We are all Charlie, we are all police, we are all Jews of France," he declared.

H/T Reddit

France Attacks Rally

People start gathering at Republique square before the demonstration, in Paris, France, Sunday, Jan. 11, 2015. (AP Photo/Laurent Cipriani)
People start gathering at Republique square before the demonstration, in Paris, France, Sunday, Jan. 11, 2015. (AP Photo/Laurent Cipriani)

France Attacks Rally

The crowd at Republique square in Paris, France, Sunday, Jan. 11, 2015. (AP Photo/Peter Dejong)
The crowd at Republique square in Paris, France, Sunday, Jan. 11, 2015. (AP Photo/Peter Dejong)

APTOPIX France Attacks Rally

A crowd gather in Republique square before the demonstration, in Paris, France, Sunday, Jan. 11, 2015.  (AP Photo/Laurent Cipriani)
A crowd gather in Republique square before the demonstration, in Paris, France, Sunday, Jan. 11, 2015. (AP Photo/Laurent Cipriani)

France Attacks Rally

Thousands of people began filling France'€™s iconic Republique plaza. (AP Photo/Peter Dejong)
Thousands of people began filling France'€™s iconic Republique plaza. (AP Photo/Peter Dejong)

APTOPIX France Attacks Rally

People watch from their roof-top apartment as some thousands of people gather at Republique square. (AP Photo/Peter Dejong)
People watch from their roof-top apartment as some thousands of people gather at Republique square. (AP Photo/Peter Dejong)

France Newspaper Attack

A child holding a ball and standing on the beach of Nice, looks at a silent march for victims of the shooting at the satirical newspaper Charlie Hebdo, Saturday, Jan. 10, 2015, in Nice, southeastern France. Ten journalists and two policemen were killed on Jan. 7 in a terrorist attack at the Charlie Hebdo headquarters in Paris. (AP Photo/Lionel Cironneau)

France Attacks Rally

French officials, with Paris mosque rector Dalil Boubakeur in a wheelchair, march in Paris, France, Sunday, Jan. 11, 2015. A rally of defiance and sorrow, protected by an unparalleled level of security, on Sunday will honor the 17 victims of three days of bloodshed in Paris that left France on alert for more violence. (AP Photo/Francois Mori)
French officials, with Paris mosque rector Dalil Boubakeur in a wheelchair, march in Paris, France, Sunday, Jan. 11, 2015. A rally of defiance and sorrow, protected by an unparalleled level of security, on Sunday will honor the 17 victims of three days of bloodshed in Paris that left France on alert for more violence. (AP Photo/Francois Mori)

France Attacks Rally

Charlie Hebdo newspaper staff, with cartoonist Renald Luzier, known as Luz, at center with moustache, march in Paris, France, Sunday, Jan. 11, 2015. (AP Photo/Francois Mori)
Charlie Hebdo newspaper staff, with cartoonist Renald Luzier, known as Luz, at center with moustache, march in Paris, France, Sunday, Jan. 11, 2015. (AP Photo/Francois Mori)

France Attacks Rally

World leaders join together in Paris during national unity march. (AP Photo/Francois Mori)
World leaders join together in Paris during national unity march. (AP Photo/Francois Mori)

France Attacks Rally

German Chancellor Angela Merkel, center, and Swiss President Simonetta Sommaruga, 2nd right, leave the Elysee Palace to join unity march. (AP Photo/Yoan Valat, Pool)
German Chancellor Angela Merkel, center, and Swiss President Simonetta Sommaruga, 2nd right, leave the Elysee Palace to join unity march. (AP Photo/Yoan Valat, Pool)

This article originally appeared on HuffPost.