Eyewitnesses have described "chaos" as they ran from the sound of explosions during suspected terrorist bomb attacks in Brussels.

Two blasts were reported at the city's airport and another at the Maelbeek metro station.

Jef Versele, 40, from Ghent, Belgium, was at the airport and described the scene as "unbelievable".

"I was on my way to check in and two bombs went off - two explosions," he said.

"I didn't see anything. Everything was coming down. Glassware. It was chaos, it was unbelievable. It was the worst thing."

He added: "People were running away, there were lots of people on the ground. A lot of people are injured."

Mr Versele was two or three storeys above the source of the explosion but he said many people around him were hurt.

"The bomb was coming from downstairs. It was going up through the roof. It was big.

Read: Brussels under attack: 13 feared dead after suspected terrorist bomb in airport and metro station

"About 15 windows were just blown out from the entrance hall," he added.

He said the emergency services were still securing the area.

Bart van Meele had planned to take a 30th birthday trip to Milan and had passed through security in the terminal when he heard an explosion.

Speaking from the airport, with sirens wailing in the background, the Apple worker, who was evacuated along with thousands of other people, said: "One of the explosions I heard, and then afterwards people started running. It's OK, I'm very calm but it's a bit crazy. You never really think it would happen to you but it's OK."

Mr van Meele, who lives in Belgium but is from the Netherlands, added: "We are all next to the airport, there are a lot of people here. I was inside the terminal, and then people started running very, very fast and then it was quiet for a time and then again they started running and it took a while before we got any information."

On the metro, traveller Evan Lamos tweeted a picture of passengers climbing from his train into the tunnel, saying: "We are being evacuated from the back of the Metro, between Schuman and Maelbeek.

"Smoke in the tunnel as we evacuate."

Brussels resident Shigeo Sugimoto said he was one stop away from where the metro was hit and heard people shouting.

He wrote on Facebook: "I am fine !! But i was in the metro when suddenly some one start shouting 'explosions!!! Evacuation!!!

"Ouch!!! I was just one station ahead before when explosion happened !!!!!!!!"

He posted pictures showing cars and people standing in the road and wrote: "Maerbeek (sic) now apocalypse!!!"

Stephanie Vanhemelryck, 24, who lives 45 minutes from the airport, described the aftermath of the attacks.

"I arrived there after the explosions happened. I pass the airport while I go to work. I get the train to work. And when I arrived there, there was an immediate evacuation."

As she was guided away from the main building, Ms Vanhemelryck said she saw several injured people, including a "few security guards injured with head wounds".

She said initially people did not seem to realise the severity of the situation, but "emotional chaos" followed.

"It was fine in the beginning but as more people started to arrive there was way more chaos", she said. "People started getting cold. People started crying."

She added: "When more people started to come outside, more emotional chaos started to happen - but not like running around. More like emotions flowing."

Mr Sugimoto said he saw a man with blood on his face in the vicinity of Maelbeek station in the EU quarter, near the European Commission's main building.

He was at Arts-Loi station, one ahead of Maelbeek, and told the Press Association: "On the ground, there were already people walking every direction to distance (themselves) from metro and the Belgian army were there trying to make people calm.

"I saw a guy, blood over his face, dragged by another person. Then police start blocking the street and I could only see ambulances go and come."