Belgian authorities say police have detained four people in a series of raids in Brussels linked to the failed bombing at a rail station this week.

The federal prosecutor's office said Thursday that the four were picked up during searches in the Molenbeek neighborhood, where many extremists have lived or transited, as well as in Anderlecht and Koekelberg.

It didn't say whether anything had been seized in the raids, and declined to provide further details.

The raids come after a man blew up a device Tuesday at Brussels Central Station that failed to fully detonate. He was then fatally shot by soldiers. No one else was hurt.

Belgium has been on high alert since suicide bombers killed 32 people at the Brussels airport and a subway station last year.