PHOTOS: Explosions rock Brussels, terror attacks kill dozens

BRUSSELS, Belgium -- Multiple explosions at two sites rocked the Brussels airport and the subway system Tuesday, killing at least 31 people and injuring at least 250.

An explosion on the rail tracks at the Maelbeek subway station near European Union offices killed at least 21 people, the city's mayor said in a news conference. Two more explosions at the departure hall of the city's Zaventem international airport killed at least 10, ABC News reports.

A suicide bomber appears to be responsible for at least one of the attacks, the Belgian federal prosecutor said. The city is now on its highest terror alert level.

Last Friday, Belgian police arrested the man suspected in the Paris terror attacks in November.

Raw video from the scene of the aftermath:

ABC News contributed to this report.

This is a developing story. Check back for updates.