Acting Spanish Foreign Minister José Manuel García-Margallo attributed the explosions in the airport and metro stations in Brussels to the terror group Isis as the city was still reeling from the devastation on Tuesday morning.
Hours later, Isis claimed responsibility for the attacks, according to reports by Reuters.
Belgian prosecutors have said that the blasts at the airport were set off by a suicide bomber and at least 23 are dead.
The Spanish Interior Ministry wrote on Twitter that the minister would hold meetings on Tuesday to assess the terror threat as well as a commission on anti-terrorism.
Retired Spanish basketball player, Juan Manuel López Iturriaga, told El Pais over the phone about his own experience at the airport's boarding area when the bombings occurred.
"We hadn't heard anything strange until suddenly people surrounded us and told us to run," he said while still waiting to be evacuated from the airport.
"At first they told us to stay in the boarding zone, later to leave and now we are waiting here for a bus to pick us up. It's all very confusing... We don't have any more information than what we read on Twitter or the internet.
"I feel a bit ill, but we have not felt fear or panic. What affects me more is that I'm so close to where there was a bomb."
The city quickly went into lockdown with the airport - an international hub - immediately closed until at least 6am Wednesday and the city's Metro system evacuated. The city's museums were also closed and the public transport system suspended.
Spanish foreign minister Margallo said in an interview with broadcaster Cadena Cope as many were first hearing about the news that he was "profoundly shaken" by the events and that he believed the explosions were attacks by Isis, according to Europa Press, which had access to the interview.
"It's a phenomenon of extraordinary gravity and is extraordinarily serious," the minister said in reference to jihadist terrorism
Just arrived at Schuman station after walking on the tracks. pic.twitter.com/4xc0YCQmIv- Evan Lamos (@evanlamos) March 22, 2016
A spokeswoman for Aena, Spain's airport operator, told The Local Tuesday morning that at that moment "there are no official plans to increase security in Spain's airports, but that could change as we get more information throughout the day".
Aena had also written on Twitter that there was one flight as of 10am heading to Brussels from Spain, but it then headed back to Barcelona. All other flights to Brussels have been cancelled or rerouted.
Madrid Metro also told The Local that: "We are working with police on all matters related to security."
Spain's acting Prime Minister Mariano Rajoy expressed on Twitter his great concern for the situation in Belgium.
"We are following the events of what happened at Brussels airport with regret and worry. All of our support and solidarity," Rajoy wrote.
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