Police hunt suspect in Brussels attacks that killed 30

At about 9 a.m. local time, an explosion was reported in the Maelbeek metro station in Brussels, in the heart of Belgium's government district near the European Council and European Parliament buildings.

Evan Lamos, a freelance video and media worker, was on a train heading into Brussels right before the blast at the metro station. "On the Metro between Schuman and Maelbeek. We have just been stopped due to an 'incident on the line'. Can hear soft thudding in distance," he tweeted.

"We felt a blast of air and my ears popped shortly after leaving Schuman station. The Metro stopped immediately," he added. He took this video of the train being evacuated in the dark after the explosion:

"Can still hear soft thudding in the distance," Lamos said, before he was evacuated through a smoke-filled tunnel.

The blasts come four days after the police in Brussels captured Salah Abdeslam, the main remaining suspect in the Paris attacks in November.

The Belgian news agency Belga reported that shots were fired and that there were shouts in Arabic shortly before the explosion. 

Sky News reporter Alex Rossi was at the airport's duty-free shop when the explosions happened.

"I could feel the building move," he said. "There was also dust and smoke as well. I went towards where the explosion came from and there were people coming out looking very dazed and shocked."

Brussels airport said that all flights for Tuesday and Wednesday had been cancelled. No trains to and from the airport were running.

Belgium's interior minister, Jan Jambon, announced that terror levels were at maximum level after the two explosions and that their absolute priority were the people still at the airport

Security at Paris train stations, metros, and airports has been reinforced, according to AFP. Belgians were warned to stay at home and to not make phone calls, as the network was being saturated with calls.

US President Barack Obama was briefed on the Brussels attacks while on an official visit to Cuba, according to a White House statement. The FBI has begun coordinating with its Belgium counterparts and other US agencies following the blasts, Reuters reports.

Eurostar confirmed that trains were running again to or from Brussels, and the STIB is working on re-opening certain metro stations.

RTBF reports that all tunnels in Brussels have been closed and that border controls at the Belgium-Netherlands border are in place. The Belgian Crisis Centre also appealed to the population: "Stay where you are."

The RTBF reports that train stations in Brussels are set up to re-open at 4 p.m. local time.

Nuclear power plants in Doel and Tihange in Belgium have been evacuated with only key staff remaining to operate the facilities. The evacuation is part of a set of safety measures related to the high-security alert in the country, Reuters reports.

According to the AFP, Sunni Islam’s leading seat of learning, Al-Azhar, condemned the attacks in Brussels on Tuesday. "Al-Azhar strongly condemns these terrorist attacks. These heinous crimes violate the tolerant teachings of Islam,” the Cairo-based organisation said in a statement.

People in Brussels and other capitals throughout the world have started to gather and set up memorials for the dozens of people killed in the attacks.

Martin Schulz, the President of the European Parliament said in a statement that Brussels would stand strong after the attacks. "I am horrified by the despicable and cowardly attacks which took place in Brussels today," he said.

"These acts anger and sadden me at the same time. They are born from barbarism and hatred which do justice to nothing and no one. Brussels, like other cities hit by such terrorist attacks, will stand strong..."