Should Brussels have seen terror attack coming?

One of the most heartbreaking elements about Tuesday's savage suicide attacks on the Brussels Airport, and the bomb packed with nails that ripped through the crowded subway car at rush hour, is the growing sense they could have and should have been stopped.

After the airport attacks, police released a picture of the suspects, casually pushing luggage, and thought to be carrying explosives, reports CBS News correspondent Charlie D'Agata.

The person in the middle has been identified Ibrahim El Bakraoui. He and his brother, Khalid, were already known to Belgian police as petty gangsters. Ibrahim was thought to have blown himself up at the airport. Khalid is the key suspect in the train bombing.

But the man in that hat has not been identified by the police. Belgian media says that's Najim Laachraoui, the suspected bomb-maker. Investigators believe he fled the airport in the chaos and may have left his bomb behind.

A bomb disposal team carried out a controlled explosion on a bomb they found at check in. Counterterror police raided an address reportedly given to them by the taxi driver who unwittingly drove the three men to the airport.

It was at that location that police said they found another bomb, more bomb-making equipment and an ISIS flag.

The images of the badly wounded sprawled outside the airport terminal has put the Belgian rescue effort under fire, too. Passenger Camilla Afreh told CBS News she was lucky she was in a different part of the terminal when the explosions rang out.

"We just missed it, literally, just missed it," Afreh said. "It was chaos, there was people crying, people screaming, people running around."

Belgians not only have to deal with the horror of what's already happened, but the real fear it might happen again.

The prosecutor said one of the bombers left behind a will, that said he was in a rush, he didn't know what to do, he felt hunted and didn't want to end up in a cell.