Three Metro Detroit men accused of planning an attack on Halloween in what the FBI says was a "potential terrorist attack" were back in federal court on Monday.

Ayob Nasser, Majed Mahmoud and Mohmed Ali, all from Dearborn, stood before a federal judge for a detention hearing.

When asked by U.S. Magistrate Judge Anthony P. Patti, each suspect agreed to detention, meaning they will remain in custody until trial. That could change as all three are given one opportunity to request to be released on bond.

All three suspects are due back in court next week for a preliminary exam.

According to a criminal complaint, investigators claim the defendants were part of a group that was purchasing assault weapons, accessories, ammunition and tactical gear online to prepare for a terror plot.

In the complaint, undercover agents say they followed the suspects to a gun range and spotted them practicing with weapons. Several AR-15 style rifles, guns and ammo were also found when investigators raided Ali's and Mahmoud's homes.

If all three defendants are indicted by a grand jury, which could come as soon as a few days, weeks or months, the court will no longer need probable cause, and the preliminary exam will not happen.

Neither the suspects' attorneys nor their families would speak to the media following the hearing.