Belgian media said police were hunting one attacker who had survived.
There was no credible claim of responsibility eight hours after the first blast; but the coordinated assault, four days after Brussels police captured the prime surviving suspect in the Islamic State attacks on Paris, turned immediate attention to local Islamists.
Seven pharma executives may be put on trial on suspicion of supplying a key ingredient for making crystal meth to a Mexican drug cartel.
Young men have been recruited by a mix of back street preachers, social media and a growing network of hometown jihadists spreading tales of derring-do in Syria.
Brussels is virtually paralyzed due to terrorist threats.
Paris fugitive Salah Abdeslam still at large.
Six murals of the Mexican artist are being exhibited in Brussels, Antwerp and Mechelen.