From Sky News Live: "Train staff say explosion has occurred at metro station in Brussels near the European Union headquarters" https://www.youtube.com/watch?v=y60wDzZt8yg
From the pictures, it looks like terrorism. Accidental explosions in the check-in lobby of an airport seem unlikely. Photos: https://www.rt.com/news/336519-explosions-hit-brussels-airpo... or http://www.standaard.be/cnt/dmf20160322_02196237
Government source [1] allegedly confirms it is a terrorist attack. Translation on Reddit [2]. 11 dead, 25 wounded. "Multiple witnesses confirm there were first shots fired, then some Arabic yelling and then 2 explosions"
From RT: https://www.rt.com/news/336519-explosions-hit-brussels-airpo...
> Reports also suggest that first there was a shot fired in the departure hall, then something was called out in Arabic, and only afterward, two explosions rocked the facility.
[1] http://www.demorgen.be/binnenland/live-zeker-een-dode-bij-ex... [2] https://www.reddit.com/r/worldnews/comments/4bgfx5/reports_o...