A major European capital on Tuesday was once again rocked by deadly terrorist attacks when bomb blasts around Brussels halted transportation, killed and injured dozens and forced the city into lockdown.

The so-called "Islamic State" (IS) terrorist organization claimed responsibility for the day's carnage, which left at least 30 people dead and around 230 injured. IS was also behind the November 13 attacks in Paris, which killed 130 people.

The first of the coordinated attacks occurred on Tuesday morning at Brussels Airport, just outside the city. Two back-to-back explosions, possibly caused by suicide bombers, erupted in the departures area, shattering windows and causing the ceiling to collapse. Media outlets showed chaotic scenes of dazed and terrified people running from the airport as smoke billowed from the top of the building. At least ten people died in the blasts and around 100 people were injured.

About an hour later, another blast tore through the Maelbeek subway station in the city center, near where many of the EU's institutions are located. At least 20 people were killed and another hundred injured, forcing police to evacuate frightened passengers through the subway's darkened tunnels.

Shock and solidarity

The attacks came just several days after Belgian police arrested Salah Abdeslam, following a police raid in the capital. Abdeslam was considered Europe's most wanted fugitive after having allegedly taken part in the November attacks in Paris. The connection led many in the media to speculate that Tuesday's bombings were a response to the arrest.

However, in a statement released soon after the blasts, IS didn't mention Abdeslam's name, instead pointing to Belgium's participation "in the international coalition against the Islamic State" as the reason for the attack.

The blasts led Brussels to lock down the city for the second time in four months, shutting down the subway and train systems. The CEO of Brussels Airport also announced that all flights would be canceled until at least midday on Wednesday, impacting some 24,000 passengers.

Yet even as shock was just starting to take hold, shows of solidarity began pouring in from around the world. The hashtag #JeSuisBruxelles - an echo of the popular #JeSuisCharlie and #JeSuisParis hastags that followed in the wake of the terrorist attacks in France last year - almost immediately started trending. Leaders in Germany and beyond condemned the violence and reiterated their commitment to defeating IS. Social media users shared images of a tearful Tintin, the iconic Belgian comic book character, as an expression of their grief.

Manhunt begins

During a press conference on Tuesday night, Belgian officials, including Prime Minister Charles Michel, said the country would ramp up border controls and launch police raids to find the culprits behind the attacks. Surveillance footage from the airport showed three men suspected of having carried out the attacks, two of whom might have been suicide bombers and the third of whom was suspected of still being at large.

Authorities discovered a third bomb in the airport, which police deactivated. Meanwhile, a police raid on a house in a district of Brussels turned up an IS flag and another bomb.

In an address to his nation on Tuesday night, Belgian King Philippe called on his people to stand united in the face of terror.

"Faced with this threat, we will continue to respond collectively, with determination, calm and dignity," Philippe said.