An explosion was heard at Maelbeek metro station in Brussels, close to the EU institutions, Belgian broadcaster RTBF said, after explosions ripped through the departure hall at Brussels airport.

Metro operator STIB announced on Twitter that the metro was closing.

Two explosions occurred at Zaventem airport in Brussels early Tuesday, at least 11 people were killed and several were injured, Belgian media reported.

Eyewitnesses said the explosion occurred in the departure hall shortly before 8 am local time.

The cause of the explosions is not known.

​All flights to the Zaventem airport in Brussels have been canceled following two explosions, local RTBF broadcaster reported Tuesday.​Rail traffic to the airport suspended.