The Werkgroep Meteoren says that it was visible as a bright sphere. The work group received more than 20 reports from people who saw the fireball within 45 minutes. This was the 5th fireball visible above the Netherlands.
Comment: The fifth? What, the fifth ever? Very unlikely! A quick search pulls up these five from recent years:
Enormous fireball seen from Belgium, The Netherlands and Germany, 13 February 2013
Meteor Fireball Explodes Over Netherlands
Fireballs seen over Germany spark UFO speculation
UK / Holland / Germany Fireball Meteor 12SEP2013
Large Fireball Over The Netherlands Raw Footage 01 18 2014
Fireballs are meteors that are much brighter than normal. They are usually seen during meteor showers. During the next few days the Orioniden shower will reach its maximum. According to the work group, the shower will probably be very visible.
The Orionidens originated in Halley's Comet, which comes close to the sun and the earth every 76 years.