Belgium is on high alert after explosions rocked Zaventem airport on Tuesday morning.

Authorities confirmed two blasts went off in the departure area just after 8 a.m. local time, at least one of which occurred near the American Airlines check-in area.

As of press time, the Belgian government reported TK injuries and TK dead, though the number of casualties reported varies by media outlets.

The Zaventem airport Twitter account immediately warned travelers to stay away and verified the first explosions. Rail services has been suspended, the airport was evacuated and all flights are cancelled. The only open roads are for emergency vehicles, according to the Belgium.be Twitter page.

Brussels Airport, located in the northeast part of the city, transported over three million passengers in February, according to the most recent traffic figures. It is also just 3.6 miles from NATO headquarters, the political and administrative center for the North Atlantic Council.

The explosions come just four days after 26-year-old Salah Abdeslam, one of the key suspects behind last November's massacre in Paris, was arrested in Belgium. Abdeslam told Belgian investigators he was planning another ISIS-related attack upon his capture.

Authorities have not confirmed whether this is a terrorist attack or whether is it related to Abdeslam, but Sky News reported that shots were fired by individuals yelling in Arabic.

Twitter First-Person Accounts

Update: 4 a.m. EST

Additions explosions were reported at at least one subway station in Downtown Brussels at about 9 a.m. local time. Footage posted to Twitter depicted a plume of smoke coming out of one of the entrances to Maelbeek metro station near the European Quarter.

The Maelbeek station is steps away from the European Commission, the legislative body of the European Union that manages day-to-day business for many of the commission's 28 member countries.

Awaiting passengers at the nearby Schumann station were forced to escape through dimly lit tunnels. Belgium officials haven't said whether an explosion went off there as well.

No trains are running to or from Brussels.

Update: 5 a.m. EST

Belgium Prime Minister Jan Jambon raised the threat level to its maximum level. This is only the second time since World War II that the threat level has reached level four, which allows for a military presence. The only other time came following the Paris attacks.

Update: 6 a.m. EST

The Office of the King's Prosecutor told RTFB, Belgium's biggest broadcaster, that the Zaventem airport explosions were part of a suicide attack.

The city is on lockdown and residents are being asked to stay indoors.