MINNEAPOLIS — Authorities said Tuesday that they are investigating after a list containing the personal information of several Minnesota police officers was posted online.

The existence of the list was first reported Monday by the news site Vocativ, which says its analysts discovered that the names, phone numbers and addresses of 36 officers had been shared on an encrypted application. Vocativ called it a “kill list,” and said it was posted by a group of hackers who support the Islamic State group.

FBI spokesman Kyle Loven would not confirm who created or posted the list, or whether it was a “kill list,” but he said authorities are looking into the facts and investigating who is responsible and a possible motive.

“We’re trying to determine who, in fact, is behind the posting of this information,” he said. Loven added that the information contains the names of officers from around Minnesota and neighboring states, but he did not give the number of officers named or the nature of the information, saying only that it was personal information officers “would prefer not be out there online.”

“Any time there’s a threat against law enforcement personnel we are going to proceed in a very serious manner,” Loven said.

St. Paul Police Department spokesman Steve Linders said the information includes officers’ names and addresses. He said four active St. Paul officers and one retired officer are on the list.

“We’ve notified the officers and we’re working with our federal partners to ensure our officers are safe,” he said. He did not elaborate on what precautions are being taken.

A spokesman for the Minneapolis Police Department said none of its officers are on the list.

Last year, another hackers’ group affiliated with the Islamic State group posted the names, photos and addresses of 100 U.S. military members online, and urged that the individuals be killed by sympathizers inside the United States. Defense Secretary Ash Carter said at the time that the information posted by that group was publicly available and had been taken from social websites.