W. intel: Up to 20 terrorist cells active in four European countries

Following the round-up of 10 jihadi cells in Belgium Thursday, a Western Intelligence source told CNN that the ongoing terror threat appears to involve up to 20 sleeper cells of between 120 to 180 people ready to strike in France, Germany, Belgium and the Netherlands. The source said that European Union and Middle East intelligence agencies identified an "imminent threat" to Belgium, possibly also to the Netherlands.

Jewish schools were closed Friday in Belgium and France.