Former Ivy League classmates John Legend and Donald Trump Jr are embroiled in a Twitter war after the musician called his father a racist.

The spat began after Trump Jr tweeted about a protest that turned violent before his father's Chicago rally yesterday.

'Ha 5 students when asked why there were protesting couldn't even answer,' Trump's eldest child wrote. 'The participation medal/micro aggression generation is pretty sad!'

Legend was quick to respond to Trump Jr, who he attended the University of Pennsylvania.

Scroll down for video

Former Ivy League classmates John Legend and Donald Trump Jr are embroiled in a Twitter war after the musician called his father a racist

The spat began after Trump Jr tweeted about a protest that turned violent before his father's Chicago rally yesterday

'I think they were protesting your racist father,' Legend wrote. 'This isn't complicated.'

'Here we go again,' Trump Jr responded. 'That can't be the answer for everything you don't like.'

'That's why the country is so divided now!' he added.

Legend hit back: 'No. It's just the answer when racist racists are saying racist s*** and are endorsed by the KKK.'

One Trump supporter then decided to insert himself in the conversation and hit back at Legend without taking a look at his Wikipedia page.

'Is John Legend that disgraceful?' wrote a Twitter user who calls himself RedKneckHillBilly.

Trump Jr was quick to respond after Legend called his father a 'racist', but Legend wouldn't back down

Legend graduated magna cum laude from the University of Pennsylvania in 1999 with a degree in English, concentrating in African American Literature and Culture

One Trump supporter then decided to insert himself in the conversation and hit back at Legend without taking a look at his Wikipedia page

The comment got a direct response from Legend, who was happy to point out that he graduated from the same university as Donald Trump Jr and his father.

Legend wasn't the only celebrity to criticize Trump following Chicago's violent night.

The musician graduated magna cum laude from the University of Pennsylvania in 1999 with a degree in English, concentrating in African American Literature and Culture.

Donald Trump Jr graduated from the university's Wharton School with a BS in Finance, Real Estate and Marketing in 2000, according to his LinkedIn page.

Legend wasn't the only musician to criticize Trump following Chicago's night of violence.

Donald Trump Jr graduated from the university's Wharton School with a BS in Finance, Real Estate and Marketing in 2000, according to his LinkedIn page

Legend (pictured with model wife Chrissy Teigen) wasn't the only musician to criticize Trump following Chicago's night of violence

He retweeted a message from Josh Groban, who wrote: 'When Trump says "I'd hate for anyone to get hurt" I can just see his miniature orange fingers crossed behind his back.'

And as word spread of Legend's comments regarding Trump, he tweeted: 'This is not controversial. This is not news. The sky is blue.'

Friday night saw unprecedented scenes inside the University of Illinois at Chicago Pavilion between an anti-Trump mob and Chicagoans who came to hear the Republican front-runner speak.

Chicago police say two officers were injured and taken to the hospital when supporters during the clashed with protesters Friday after Donald Trump abruptly canceled a campaign rally.

Around 10,000 protesters were to said to have RSVP'd to the event.

News of the shutdown in Chicago came hours after a black activist in St Louis, who gave his name as Anthony Cage, was filmed being escorted into a police van by cops with blood across his face and down the front of his sweater after clashing with Trump supporters.

After the campaign event was officially canceled, raucous protesters spilled out onto the street of Chicago and clashed with law enforcement officers.

Police confirmed at least six arrests. One journalist was reportedly detained as well.

'It is unfortunate that parties on both sides allowed their political views to become confrontational,' Police Interim Superintendent John Escalante said Friday night.

Tensions reached breaking point as Trump's Chicago rally was forced to be shut down after a series of physical brawls and loud demonstrations