Two explosions occurred at the city's airport. Several people were killed, according to the country's public broadcaster, RTBF. Initial reports say up to 10 people were killed and more than 30 people were injured.

Another blast at a subway station occurred in the suburb of Maalbeek, near the European quarter, where much of the European Union is based, according to CNN affiliate RTL. All metro stations in the city have been closed, according to the official Twitter account for the city's transportation agency.

The Belgian crisis center tweeted that all public transportation in the city has been closed. 

Kristalina Georgieva, the vice president of the EU Commission, said that all the organization's institutions are at "alert level orange" and that all meetings on its premises and outside have been canceled.

She advised people to stay at home or indoors.

Federal police at the airport at Zaventem told CNN that "there has been an explosion" and "something has happened."

Dozens of people have been taken on stretchers out of the airport, according to eyewitnesses.

The Brussels airport tweeted that there have been two blasts and said that "the building" is being evacuated. They also said all airport operations have been suspended and asked those nearby to remain calm.

(Content source: CNN.com)