A series of blasts throughout Brussels on Tuesday have killed multiple people.

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.

It’s unclear what caused the blasts, or if they’re related to terrorism, although multiple reports say that continuous slogans of “Allah Akbar” in Arabic were heard inside the airport just before the blasts went off.

There have also been reports of atleast a couple of suicide vests recovered from the Brussels International Airport as well as the Tube.

Authorities are now claiming that it was a Fidayen atack.

Brussels was scheduled to host the European Union meet in the next few weeks in which world leaders from all over the world were confirmed in attendance.