A police raid in Belgium left two terror suspects dead and one in custody after a firefight with authorities last Thursday.

Those targeted by the raid had been under surveillance after recently returning to Belgium from Syria. A senior Belgian counter-terrorism official confirms that the attacks were ordered by the Islamic State to carry out in Belgium and Europe in retaliation for the U.S-led airstrikes against the militants in Syria and Iraq.

The raid took place in Verviers, which is about 80 miles from Belgium’s capital of Brussels. While there is no known connection between this raid and the attacks last week in Paris, European leaders have expressed concerns of citizens bringing their war home when returning from the Middle East.

In response and in preparation of future attacks, Belgium raised their national terror alert level from two to three, the second-highest level.