Denmark ? Danish police arrested eight suspected Islamic militants Tuesday in Copenhagen, charging two with planning a terrorist attack and attempted murder in what was described as a serious plot with direct ties to al-Qaida.

Police evacuated a building in the Danish capital before searching an apartment, where they found large quantities of explosive materials. The chief of the police intelligence service held an unusual news conference in which he underscored the urgency of the threat and alleged foreign connections of the suspects, six of whom hold Danish citizenship.

The arrests “prevented a terrorist attack,” said chief Jakob Sharf, who termed the suspects “militant Islamists with international contacts.”

“The fact that the suspects have a connection to leading members of al-Qaida is a very significant aspect of this case,” Sharf added. He did not identify the leaders or the target of the alleged plot.