Kirkuk (IraqiNews.com) Islamic State militants are vowing more drive-through attacks in Europe and the United States through an internal declaration circulated in Kirkuk province, a security source said Friday.

Alsumaria news quoted the source saying that Islamic State preachers had given out a text sermon in Hawija, the group’s largest haven in southwestern kirkuk, threatening the United States and Europe with more attacks by “the spurred horses” that “hit infidel masses”, in a reference to vehicles operated by group-affiliated attackers who have driven through street gatherings in Europe and the United States over the past months, killing and injuring many.

The circulated bulletin said “foreign elements and cells had been formed to target gatherings and vital commercial centers at those countries” in response to “strikes by the alliance of infidels and apostates on the Caliphate’s locations,” as the text quoted by the source put it.

The report comes a few hours after at least 13 were killed in central Barcelona when a driver rammed into a crowd of civilians on Thursday in Las Ramblas.

Islamic State claimed responsibility for the attack after Spanish authorities had already said they were dealing with the incident as a terrorist attack.

The group had also been behind several attacks over the past years which followed its 2014 declaration of a self-styled “caliphate” in Iraq and Syria.

A military alliance of more than 60 countries, led by the United States, has been waging airstrikes and ground offensives against IS locations in Iraq and Syria.