A lone attacker tried to smash his car through the gates of an army barracks in southern Belgium and fled in the vehicle after shots were fired, Belgium's defense minister said Monday.

Defense Minister Steven Vandeput said the intruder's motive was unclear but insisted "it is certainly an aggression targeting the barracks."

Belgium has been one of the largest recruiting bases per capita for foreign fighters traveling to join ISIS, and authorities have openly expressed alarm about what the recruits might do if they return.

Police detained a suspect three hours after the attack following a manhunt which also involved helicopters, said prosecutor's spokesman Vincent Macq.

Since a gunman killed four people in the May 2014 attack on the Jewish museum in Brussels, Belgium has been on higher alert for further extremist attacks. Police killed two men and arrested a third in January in a counter-terrorism raid in the eastern city of Verviers.

Monday's incident occurred near the French-speaking town of Namur, south of Brussels. The suburb of Flawinne is the site of one of Belgium's major military barracks, home to the 2nd Commando Battalion.

Because of the higher alert, the military immediately "fired some 10 warning shots," said Vandeput.

Afterward, security personnel immediately swarmed the area.

"Within the next 30 minutes it was a madness. Military going all over the place, police vans, special operation task forces, and at around 11 a.m. the bomb squad arrived, and we were asked not to stay around," said Fabienne Botilde, who lives near the entrance to the barracks.

There were no reports of serious injuries at the barracks. A busted-up Ford was found close by the barracks which police carefully investigated.

A preliminary report this month from a U.N. Working Group on the Use of Mercenaries estimated 500 people have been recruited from Belgium to fight in Iraq and Syria.

The Associated Press contributed to this report.