BRUSSELS (AP) — Belgian authorities detained a suspect who was driving a car with gas canisters in his trunk Thursday, setting off a security alert in the center of Brussels.

The prosecutor's office said a busy part of the capital was closed off and a subway station closed during the evening rush hour.

Prosecutor's spokeswoman Ine Van Wymersch said authorities did not want to take any chances and acted quickly "since the driver was known by judicial authorities and it was unclear why the gas canisters were there."

"We are taking the case seriously," Van Wymersch added. She said the suspect was being interrogated.

Saint Gilles Mayor Charles Picque described the driver as "a radicalized person, so it was normal to take precautionary measures."

Van Wymersch cautioned however not to jump to conclusions about a possible extremist motive.

The gas canisters were discovered when police noticed a car speeding and running red lights and pursued it.

The local transport authority said late Thursday that the Porte de Hal metro station closed on police orders, while a perimeter was established above ground. Media reported an anti-bomb squad was brought in.

Belgian security services have been on high alert since suicide bombers attacked the Brussels airport and subway last March 22, killing 32 people.