Story highlights 16 people were killed in the suicide bombing in the Maelbeek metro station

16 were killed at the airport in twin bombings an hour earlier

Brussels (CNN) An order to close the Brussels metro ahead of the deadly March terror attacks on the network failed to reach relevant authorities, in part because an email from Belgian federal police was sent to the wrong address, a parliamentary commission has heard.

The commission, established to investigate the March 22 bombings and whether they could have been prevented, heard this week that the senior police official in charge of Brussels' metro networks first learned more than an hour before the deadly bombing at Maelbeek metro station that the explosions at the city's airport were a terror attack.

JUST WATCHED Source: Paris, Brussels attackers eyed Euro 2016 Replay More Videos ... MUST WATCH Source: Paris, Brussels attackers eyed Euro 2016 02:11

At 8:03 a.m. local time -- five minutes after the twin blasts at Brussels' Zavantem airport that killed 16 -- Jo Decuyper, chief of railway police for the Brussels region, was informed by military sources at the airport that the blasts were suicide bombings, the commission heard.

A third attacker struck the Maelbeek metro station in central Brussels at 9:11 a.m., killing 16 others.

ISIS claimed responsibility for the attacks.