WATCH: Donald Trump Reacts to Brussels Terror Attacks

'Equivalent to an Attack on Washington': Expert Explains How Brussels Is 'Symbolic'

LOOK: Presidential Candidates React to Brussels Terror Attacks

UPDATE 12:01PM ET: ISIS has reportedly claimed responsibility for the terror attacks in Brussels.

ISIS sympathizers immediately flocked to social media to celebrate the Brussels terror attacks.

Benjamin Hall reported on "America's Newsroom" that ISIS-linked accounts are using the #BrusselsOnFire hashtag to express their happiness in the wake of the attack.

Hall noted that this is reminiscent of the #ParisOnFire hashtag that was used following November's deadly attacks in the French capital.

Newsweek reported:

“We are not just clapping, but we are happy again. We are smiling, we are laughing and we are joyful like it’s a day of celebration,” tweeted one ISIS sympathizer.

Another wrote: “#Brussels, if you continue your war against the religion of Allah then this is our response.”

The same user also condemned other Muslims for showing respect for the victims of the attacks, writing: “Dog Arabs condemning the killing of the Crusaders in Belgium but did not cry for half a million Syrians and a million Iraqis and tens of thousands in Burma and Mali. Your turn is coming miscreants.”

Some other users used the hashtag “#Belgium_is_on_fire_from_explosives” on Twitter as a sign of celebration at the deadly attacks.

Hall told Bill Hemmer that ISIS may be behind the attacks but has not claimed responsibility either because they are waiting for their operatives to escape or because the operation may still be in progress.

Watch more above.

'It Comes with the Territory': Eric Trump Speaks Out on Threatening Letter

'The Barrier to Peace Is Not Israel': Cruz Slams Trump Over 'Neutral' Comment

WATCH: Trump Offers Woman a Job in the Middle of His Press Conference