Two loud explosions were heard in Brussels as police launched major search operations in the Belgian capital in the wake of the suicide attacks in the city.
The explosions were heard at the start of the operation in the neighbourhood of Schaerbeek, Al Jazeera reported. A man was "neutralised", state broadcaster RTBF said.
Six suspects were arrested on Thursday.
Suicide bombers hit the Zaventem airport and a metro train station on Tuesday, killing over 30 people and wounding at least 270 in the worst such attack in Belgian history.
The Islamic State militant group claimed responsibility for the attacks.