Around 0700 GMT: Two blasts hit Zaventem international airport outside Brussels. Witnesses said they first heard shots in the departure hall before someone shouted in Arabic and then two explosions occurred.
Shortly before 0800 GMT: Police say 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 rocks the Maalbeek metro station near the EU headquarters. Around a dozen injuries are reported at first.
0815 GMT: Belgium moves to its highest level of terror alert.
0900 GMT: The European Commission tells staff to stay home or in their offices.
0900 GMT: The federal prosecutor’s office issues a casualty toll of 13 dead and 35 wounded at the airport.
0930 GMT: The crisis centre asks inhabitants to stay put, and all public transport systems grind to a halt.
Security is reinforced at airports, train stations and public transport systems in Paris, while airports in Frankfurt, London, Moscow and the Netherlands beef up their measures too.
1000 GMT: Fire services say 21 people have died, including 11 at the airport.
High-speed Thalys trains between Belgium, France and the Netherlands stop running.
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.
1115 GMT: Brussels transport operator says the metro blast killed 15 people and wounded 55, including 30 seriously.
Eurostar train service between London and Brussels is suspended.