The names of average Americans have begun to appear on “kill lists” published by supporters of the Islamic State group, the Wall Street Journal reported Tuesday.

The long lists from sympathizers of the group also known as ISIS contain the names, home addresses, email addresses and phone numbers of average Americans who reportedly have no links to the U.S. government. ISIS has encouraged its members and supporters to target people named on the lists.

Authorities have notified the people whose names have been included but remain unsure if the lists pose a serious threat or are meant to be used as a scare tactic by the Islamist group. More than 2,000 New Yorkers were named on one list released at the end of April by the United Cyber Caliphate, and approximately 1,500 Texans were named on another. Those named on the New York list included stay-at-home mothers and media executives.

“They’re putting out the lists that they are finding online and they’re sending it to their followers and they are saying these are good people for you to attack,” Thomas Galati, chief of intelligence for the New York Police Department, told the Wall Street Journal. “You can’t discount it.”

ISIS has issued “kill lists” through its social media channels for more than a year, but authorities said the length of the lists has increased and targets have shifted from people with links to the government and military to average citizens. No person named by ISIS on its lists in the U.S. has been killed.

The U.S. has been fighting ISIS in Iraq and Syria since 2014 primarily through airstrikes as part of a coalition effort. Government officials said last month that the number of ISIS members has significantly decreased.

“In fact, we assess Daesh’s numbers are the lowest they’ve been since we began monitoring their manpower in 2014,” Deputy U.S. Secretary of State Antony Blinken said, using another name to refer to ISIS, before the U.S. Senate in April. 

The CIA estimated in 2014 that as many as 31,500 ISIS fighters were on the ground in Iraq and Syria. The group has successfully utilized social media to communicate with its followers and attract recruits. Studies have estimated as many as 20,000 foreign fighters have joined ISIS, with as many as 4,000 recruits coming from Western Europe.