French authorities say they prevented a suspected bomb attack in Paris early Saturday after police arrested a man who was allegedly preparing to detonate a homemade explosive outside a United States bank.

The incident occurred around 3:30 a.m. local time in front of a Bank of America building in the 8th arrondissement, not far from the Champs-Elysees.

According to sources close to the investigation, officers moved in as the suspect placed a device believed to contain fuel and an ignition system.

The device reportedly included about five litres of liquid, thought to be fuel, along with an ignition component that contained an estimated 650 grams of explosive powder. It has since been taken to a forensic laboratory in Paris for detailed analysis.

France’s national counter-terrorism prosecutor’s office confirmed that it has taken charge of the investigation and that the suspect remains in police custody.

Authorities said the case is being treated as an attempted attack involving fire or other dangerous means in connection with a terrorist undertaking, as well as a suspected terrorist conspiracy.

Both the Paris judicial police and the country’s domestic intelligence service, the General Directorate for Internal Security, are involved in the ongoing investigation.

Interior Minister Laurent Nunez praised the swift response of security forces, noting that heightened vigilance remains in place due to the prevailing international security situation, particularly the ongoing conflict in the Middle East. He added that France continues to maintain a high level of alertness amid growing security concerns across Europe.