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 acted quickly as a precaution “since the driver was known by judicial authorities and it was unclear why the gas canisters were there.” Van Wymersch said a bomb squad carried out two controlled explosions involving items from the car while the suspect was being interrogated. No detonator or explosives were found, and only one of the two gas canisters was full, she added. Saint Gilles Mayor Charles Picque described the driver as “a radicalized person, so it was normal to take precautionary measures.” However, Van Wymersch cautioned not to jump to conclusions about a possible extremist motive. The canisters were discovered after police pursued a car they observed speeding and running red lights. 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. Belgian security services have been on high alert since suicide bombers attacked the Brussels airport and subway last March 22, killing 32 people.