Police have arrested a man wearing a “long coat and wires” in Brussels, prompting fears that he could have been a terrorist. However, a statement by authorities later said the man was simply studying waves and radiation.

The man was arrested by special units and taken to a nearby police station, said Christian De Coninck, a spokesman for the Brussels-Ixelle police, as quoted by Le Vif.

Prior to being arrested, the man was kept under armed police guard for hours, near a library adjacent to the Royal Monnaie Opera, AP reported.

"A person wearing a long coat, with wires coming out, is considered the suspect," Brussels police spokesperson Ilse de Keere said, as quoted by Le Soir media outlet.

Of course the day I reach brussels there's a terrorist threat outside my hotel window #brussels#Monnaiepic.twitter.com/d7IKSFf5uy — Adrian Imbert (@AdrianImbert) July 20, 2016

De Coninck stressed to VTM that the man's attire was "not normal at these temperatures," adding that special units would examine "what exactly is under the jacket."

However, the "very passive and very suspect" man was actually studying waves and radiation in the city, De Coninck later said.

A bomb squad arrived at the scene after police were alerted to the individual, and shops in the vicinity were evacuated.

An employee from the nearby Galerie Anspach shopping mall told RT that workers had seen "an enormous amount of police cars but we heard nothing, no shots..."

A theater employee by the name of Nicolas told RT: “All I know is that police reacted to a suspect with a suicide belt, they tried to arrest him but police [don't] want to share any more information...people here were frightened. They found out that there was something about a suicide belt and panicked and began to run..."

Several streets were blocked.

UPDATE: Police are hunting for a suspicious person seen near the Place de la Monnaie, Police operation ongoing pic.twitter.com/QXYNQqFOeJ — News_Executive (@News_Executive) July 20, 2016

Photos from the spot showed a man kneeling with his hands up, surrounded at gunpoint by security services.

The man was reported to authorities by a security guard from a private security company, according to VTM.

The bomb squad which was dispatched to the area had to use a robot that carried out an initial check and detected metal plates under the man’s coat.

The man that made the commotion is an Iranian PhD student from Ghent University, who is taking part in a research that aims to compare levels of radiation in the city to those in the countryside, Belgian Libre Belgique reported.

The student doesn’t speak Dutch or French, which are two of Belgium’s three official languages, which led to the misunderstanding. However, he is fluent in English, the university administration stressed. He had all necessary papers for the research on him, but failed to clarify the situation right away.

“The way in which he reacted initially was not normal, which is why we had to use such measures,” the spokesman explained, according to Reuters.

It comes just four months after terror attacks on the Belgian capital left 32 people killed and more than 300 injured at Brussels Airport and Maalbeek metro station. Islamic State (IS, formerly ISIS/ISIL) claimed responsibility for the attacks.

A gruesome terror attack in Nice, France, left 84 people dead and over 300 injured last week, when the driver of a truck plowed down spectators of a Bastille Day fireworks show. IS claimed responsibility.