Brussels: Bombings claimed by the ISIS group at Brussels airport and on a metro train left around 35 people dead and more than 200 injured in the city that hosts NATO and EU headquarters.
Belgium has launched a hunt for a suspect captured by surveillance cameras pushing baggage trolleys with two other men suspected of being the airport suicide bombers.
The blasts occurred four days after the arrest of Salah Abdeslam, the prime suspect in the Paris terror attacks also claimed by ISIS terrorists.
Here is a timeline of what has happened so far on Tuesday:
Around 8:00 am (0700 GMT): Two blasts hit Zaventem international airport. Witnesses say they heard shots in the departure hall before someone shouted in Arabic and then two explosions occurred.
Shortly before 0800 GMT: Police say at least one person is dead and several others wounded.
The airport is closed and a crisis cell meets at the interior ministry.
Shortly after 0800 GMT: A third explosion hits a train in Maalbeek metro station near EU headquarters. About a dozen injuries are initially reported.
0815 GMT: Belgium moves to its highest level of terror alert.
Shortly before 0900 GMT: The European Commission tells staff to stay home or in their offices, and a similar appeal is later made by the Belgian crisis centre to all Brussels residents.
Shortly after 0900 GMT: The federal prosecutor's office issues a toll of at least 13 dead and 35 wounded at the airport.
Shortly before 0930 GMT: All public transport grinds to a halt.
Shortly before 1000 GMT: The high-speed Thalys train service between Belgium, France and the Netherlands stops running. Airports in cities including Frankfurt, London and Moscow beef up security. The border between Belgium and the Netherlands is reinforced.
1015 GMT: European Council President Donald Tusk condemns the "terrorist attacks".
Shortly before 1030 GMT: Police and soldiers reinforce security around Belgium's nuclear power plants.
1045 GMT: Belgian Prime Minister Charles Michel condemns the "blind, violent and cowardly" attacks.
Shortly before 1100 GMT: Federal prosecutor Frederic Van Leeuw says one airport blast was "probably caused by a suicide bomber".
1100 GMT: "The whole of Europe has been hit," says French President Francois Hollande.
1115 GMT: Brussels transport operator STIB says the metro blast killed at least 15 people and wounded at least 55.
Eurostar train service between London and Brussels is suspended.
1235 GMT: Authorities "fear that people are still at large," says Belgian Foreign Minister Didier Reynders.
1330 GMT: Brussels mayor Yvan Mayeur says there are "around 20" dead with another 106 wounded at the metro station.
1345 GMT: A fire service spokesman says the airport attack killed 14 people and left more than 90 wounded, and warns the toll could rise.
1425 GMT: US President Barack Obama condemns the "outrageous" attacks, while major US cities ramp up security.
1500 GMT: The Belgian government declares three days of mourning.
Shortly after 1500 GMT: Media publish video surveillance pictures of the airport bombing suspects, three men pushing luggage trolleys.
1550 GMT: Leaders of the 28 EU nations say in a rare joint statement that the bombings were an "attack on our open democratic society."
1600 GMT: UN Secretary General Ban Ki-moon condemns the "despicable" attacks.
1615 GMT: Third bomb failed to explode at Brussels airport, says Brussels governor.
1640 GMT: The Islamic State group claims responsibility, saying "soldiers of the caliphate" carried out the attack against "the crusader state" of Belgium.
1715 GMT: Belgian police issue a wanted notice for an airport attack suspect.
Around 1730 GMT: The Eiffel Tower is lit up in Belgium's national colours.
1740 GMT: Belgium's federal prosecutor says the airport assault may have been carried out by two suicide bombers and the police are "actively looking" for a third attacker.
1745 GMT: Police raids are under way across Belgium and several witnesses being questioned, the federal prosecutor says.
2030 GMT: The Brussels airport attackers "came in a taxi with their suitcases, their bombs were in their bags," local mayor says.
