The transport network in the Belgian capital has been shut down
At least 20 people have been killed after a rush-hour explosion at a metro station close to EU buildings in Brussels.
Footage of the blast at Maalbeek station showed black smoke pouring from the entrance, with people being moved on stretchers and victims seen with facial injuries.
Passengers were evacuated from trains in the tunnels around Maalbeek and led along tracks to other stations.
Public broadcaster VRT reported 20 people were killed in the metro explosion. Transport operator STIB said another 55 people were injured. Ten of the wounded were reportedly in a critical condition.
Video footage showed passengers being helped out of a train carriage as children could be heard screaming as they were led to safety.
Pierre Meys, a spokesman for the Brussels fire brigade, said there was an "enormous explosion".
He added: "Most of the wounded have been evacuated. The scene is rather chaotic".
The federal prosecutor's office in Brussels confirmed that the three blasts which hit the capital on Tuesday were terrorist attacks.
Alexandre Brans, who was wiping blood from his face, said: "The metro was leaving Maalbeek station when there was a really loud explosion.
"It was panic everywhere. There were a lot of people in the metro," the 32-year-old said.
One of those inside the offices of the EU Parliament is Sinn Féin MEP Lynn Boylan.
Just arrived at Schuman station after walking on the tracks. pic.twitter.com/4xc0YCQmIv— Evan Lamos (@evanlamos) March 22, 2016
The cause of the explosion has not yet been confirmed, but it coincided with a suicide attack at Brussels Airport.
VRT said the blast went off on a carriage on an underground train which had stopped at the station.
Ian McCafferty, who was at the next station Arts Loi, said: "I was getting off at the metro station at Loi when we heard a muffled thud and a lot of debris was thrown up".
Authorities shut metro, train, tram and bus services in the Belgian capital following the bomb blasts and the country raised its terror alert to the highest level in the wake of the attacks.
Major rail stations were also closed and Eurostar said no trains would be running to or from Brussels Midi.
The UK, Netherlands and France announced that security at transport hubs and on borders would be increased in the wake of the explosions.