The Brussels public transport operator said 15 were killed on board the metro train and 55 injured.

Pierre Meys, a spokesman for the Brussels fire brigade, told AFP 11 people died in twin blasts at Brussels airport.

There were also “around ten killed at the Maalbeek metro station where there was an enormous explosion,” he said.

“Most of the wounded have been evacuated. The scene is rather chaotic,” he said earlier today.

The Belgian health minister later confirmed a further 81 were wounded, Reuters reported.

The blasts came just after 8am when two explosions ripped through Brussels airport at Zaventem’s departures hall, reportedly at aisle eight.

About an hour later an explosion at Maelbeek metro station in central Brussels, near the European Union offices, caused injuries in chaotic scenes reported on social media.

All public transport in Brussels and flights to the Belgian capital have been stopped, Reuters reported.

‘Terrorist attacks’

Hours after the attacks Islamic State used its online news agency to claim responsibility for the deadly attacks.

“Islamic State fighters carried out a series of bombings with explosive belts and devices on Tuesday, targeting an airport and a central metro station in the centre of the Belgian capital Brussels, a country participating in the international coalition against the Islamic State,” the Aamaq news agency said.

Belgian federal prosecutor Frederic Van Leeuw has called all three explosions in Brussels “terrorist attacks”.

“One attack was probably done by a suicide bomber,” Van Leeuw said at a mid-morning press conference held today in Brussels.

Belgian Prime Minister Charles Michel said authorities were worried there will be more attacks and border controls have been reinforced.

“We realise we face a tragic moment. We have to be calm and show solidarity,” Michel said.

“What we had feared has come to pass. Our country has been struck by attacks that are blind, violent and cowardly.”

Zaventem Airport explosions

Video footage taken at the scene showed terrified passengers fleeing the terminal building as smoke billowed overhead.

In graphic images posted online from inside the departures terminal, a false ceiling and shattered glass litter the floor as bodies lie covered in dust. Security officers are also seen.

Shots were heard shortly before the explosions at Zaventem Airport, according to Belgian media.

All passengers were evacuated from the airport and rail traffic to the terminal was suspended.

Flights were diverted to Liege and other European cities while international rail services to Brussels like Eurostar were cancelled.

Social media showed pictures of smoke rising from the departure hall where all windows had been shattered by the blast. Passengers were seen running away down a slipway from the departure lounge.

Sky News television’s Alex Rossi, at the scene, said he heard two “very, very loud explosions”.

“I could feel the building move. There was also dust and smoke as well...I went towards where the explosion came from and there were people coming out looking very dazed and shocked.

“The thinking here is that it is some kind of terrorist attack – that hasn’t been verified by any of the authorities here at the airport.”

In a tweet, an airport spokesman warned people to stay away from the airport.

He said: “Don’t come to the airport – airport is being evacuated. Avoid the airport area. Flights have been cancelled.”

Metro blast

There were further reports of a blast on the Brussels metro at Maalbeek station near the European Union headquarters, AFP reported.

Pictures on social media show people being helped from a metro train in a smoky, dark tunnel and casualties outside the entrance to the station.

Evan Lamos, who posted to Twitter that he was riding a metro train as the blasts occurred, said: “We felt a blast of air and my ears popped shortly after leaving Schuman station. The Metro stopped immediately.”

Lamos said he walked through the smoky tunnel to Arts-Loi station after hearing thuds.

Amber alert for travelling Hongkongers

The Immigration Department said it had not received any reports from Hongkongers seeking assistance following the Brussels attack, but said it is monitoring the situation with travel agencies and mainland authorities in China and Belgium.

Belgium authorities raised the nation’s terror alert level to its highest setting and urged the Brussels public to stay indoors.

Hong Kong raised an amber travel warning for Belgium, the lowest on the scale of safety warnings, in response to the attack.

The Security Bureau’s outbound travel advice said: “Residents who plan to visit the country or are already there should monitor the situation, exercise caution, attend to personal safety, avoid travelling to places of large gatherings of people.”

Britain and the United States also issued similar warnings in the wake of the triple blasts.

The number of Hongkongers in Brussels is not yet known. Residents who needs assistance from the Hong Kong Immigration Department in relation to the attacks can call (+852) 1868, 24-hours.

Terror arrests

The blasts occurred four days after the arrest in Brussels of a suspected participant in November militant attacks in Paris that killed 130 people. Belgian police had been on alert for any reprisal action.

Brussels Airport serves more than 23 million passengers every year.

It comes just four days after Salah Abdeslam, the prime surviving suspect for November’s Paris attacks, was captured by Belgian police after a shootout on Friday.

Belgium’s Interior Minister, Jan Jambon, said on Monday the country was on high alert for a possible revenge attack following the capture of 26-year-old Abdeslam.

“We know that stopping one cell can ... push others into action. We are aware of it in this case,” he told public radio.

French investigator Francois Molins told a news conference in Paris on Saturday that Abdeslam, a French citizen born and raised in Brussels, admitted to investigators he had wanted to blow himself up along with others at the Stade de France on the night of the attack claimed by Islamic State; but he later backed out.

‘We are at war’: France reacts

French President Francois Hollande said the attacks in Brussels on Tuesday that killed at least 26 people struck at “the whole of Europe”.

“Through the attacks in Brussels, the whole of Europe has been hit,” Hollande said in a statement, urging the continent to take “vital steps in the face of the seriousness of the threat”.

French Prime Minister Manuel Valls said: “We are at war. Over the past few months in Europe we have endured several acts of war.”

France, which neighbours Belgium to the south, was hit by two major terror attacks in 2015 and several of the jihadists behind them came from Brussels.

“France will implacably continue the fight against terrorism both on the international level and at home,” said Hollande.

Attacks on November 13 in Paris claimed 130 lives, 10 months after attacks on the satirical newspaper Charlie Hebdo and a Jewish supermarket left 17 dead.

French Interior Minister Bernard Cazeneuve earlier announced that Paris was deploying 1,600 additional police to border crossings and air, sea and rail infrastructure after the Brussels attacks.

Germany and the Netherlands also announced stepped up security measures at borders, airports and rail stations.

— with Reuters, AFP