The Federal Bureau of Investigation is investigating approximately 300 refugees in the U.S. for terrorism, a Department of Homeland Security official told reporters Monday.

The official said this was “truly an alarming number,” and added that there are also approximately 1,000 investigations into potential domestic terrorists inspired or motivated by ISIS.

[dcquiz] Two terrorist attacks by Somali refugees have injured more than 20 Americans in the past year. The DHS also pointed Monday to the case of another Somali refugee who was sentenced to 30 years in prison in 2014 for trying to set off a bomb at a Christmas tree-lighting ceremony in Portland, Ore.

The announcement from the DHS official, speaking on the condition of anonymity, came as President Donald Trump signed an executive order that would temporarily stop refugee admittances for 120 days.

More than 4,300 refugees have entered the country in the past month since a federal judge blocked Trump’s previous order stopping refugee entry. This new executive order will be effective on March 16, and during the halt in refugee entry, the government will review vetting procedures.

Unlike the previous executive order, the one signed Monday has no indefinite ban on Syrian refugee entry.