Just four months after the horrific terror attacks in Paris that killed 130, Brussels was rocked by multiple explosions that ripped through Zaventem Airport and Maelbeek metro station on Tuesday, 22 March, killing at least 34 people and leaving 170 injured.

People from around the world are showing solidarity with the victims and grieving Belgian people by flooding social media with messages of support. Although Facebook has not yet rolled out an overlay of the Belgium flag for profile pictures like it did for the Paris attacks, people have already begun doing so through alternative apps and tools.

Here's how you can change your Facebook picture to feature the colours of the Belgian flag:

1. Visit the Belgium Flag Overlay Facebook page and click on the link to their app.

2. Click on the "Start — Connect to Facebook" button. It will ask if it can access your profile to proceed.

3. After you do so, you are then brought to a page where the overlay is already featured on your profile picture. Adjust the orientation and opaqueness.

4. When you are satisfied with the photo, click next and follow the rest of the steps to publish your new profile picture.

The small yet empowering digital gesture first became popular in June 2015 as a way to show support for same-sex marriages.

However, the trend does have its fair share of critics as well:

Facebook switched on its Safety Check feature, which allows users to easily alert their loved ones that they are safe amidst the attacks, three hours after the Brussels attacks began. Google has offered free calls to Belgium via Hangouts, Hangout Dialer and Google Voice. Many in Brussels are using the hashtag #ikwelhelpen (which means 'I want to help' in Dutch) on social media after the deadly attacks to offer temporary housing and transportation to those stranded in the Belgium capital.