Expert answers your questions about Brussels attacks
24 March 2016 Last updated at 16:56 GMT
BBC security expert, Frank Gardner, has answered your questions about a number of attacks which took place in Brussels, the capital city of Belgium, on Tuesday.
Sadly, at least thirty-one people died and others were hurt in the explosions.
Hundreds of messages of support to the people affected have been written in chalk in a square in the centre of Brussels.
Some of you might be feeling worried about what has happened, so we asked BBC security expert Frank Gardner to answer your questions about the attacks.