authorities say this was an active terror cell they've been monitoring for weeks when they realized an attack was imminent. they were reportedly plotting to attack police buildings on a grand scale, according to belgian authorities. the gunfire in belgium comes just a week after the attacks in paris that killed 17 people. there's no link so far between the two, but the hunt for accomplices in the paris incidents has put a jittery europe on heightened alert. there are also reports that weapons used in the paris attacks were purchased in belgium. amedy coulibaly, who prosecutors say killed four people in a kosher supermarket, is said to have bought automatic weapons and rocket launchers around brussels. belgium has one of europe's highest rates of nationals going to syria to join the jihad, and many have appeared in propaganda videos like this one.