PARIS — French police stopped a suspected bomb attack outside a Bank of America building in Paris, arresting four individuals in the early hours of Saturday morning. The French counterterrorism prosecutor's office said the four are suspected of terrorist criminal conspiracy in a case believed to have links to Iran.

Police officers conducting surveillance outside the bank spotted two individuals near the entrance early Saturday. Officers arrested a 17-year-old suspect at the bank entrance and recovered a homemade bomb made of a gasoline-filled container taped to a powerful firework in front of the building. Forensic experts said the device contained 650 grams of explosives, a type they said had not previously been encountered in France, and that it could have produced a large fireball.

Police later arrested two other 16-year-old suspects and one adult previously convicted of drug trafficking. A fifth person was detained but released without charge. The three minors have no prior criminal records and denied any terror-related intent.

Prosecutors said analysis of CCTV footage, the suspects' digital media, mobile phone data, and their statements showed that the three minors were recruited by the adult the previous week to place and ignite the device at the bank entrance and film the scene. The adult recruited the minors in exchange for payment of 500 to 1,000 euros, prosecutors said.

Prosecutors formally opened a judicial investigation on preliminary charges of terrorist criminal conspiracy, building, possessing and transporting an explosive device, and attempted destruction as part of an organized group in connection with a terrorist enterprise. They requested that all four suspects, including the three minors, be placed in detention pending trial.

A video circulated on social media on March 23 that specifically mentioned the Bank of America offices in Paris as a potential target. The video was attributed to a pro-Iran group known as Harakat Ashab al-Yamin al-Islamia, which translates as the Islamic Movement of the Companions of the Right. The prosecutor's office said the foiled attack appears likely linked to the group, though this has not been formally established.

The group has claimed responsibility for other actions across Europe, including in Belgium and the Netherlands, as well as a recent attack in London in which four ambulances belonging to a Jewish charity were set on fire. London counterterrorism police announced three additional arrests Wednesday in connection with the ambulance attack. Two men were previously released on bail after being detained in that probe.

French authorities have increased security around key individuals and sites and have provided personal protection for some people from the Iranian opposition. Interior Minister Laurent Nuñez said that Iran's intelligence services habitually use proxies to carry out actions abroad targeting U.S. interests, the Jewish community, and Iranian opposition figures.