A shooting on Fort Berthold Reservation in New Town, N.D., has left a grandmother and her three grandchildren dead, authorities said. A suspect who was being questioned killed himself hours after the shooting. 

According to The Associated Press, authorities said the victims are Martha Johnson, 64, Benjamin Schuster, 13, Julia Schuster, 10, and Luke Schuster, 6. Johnson and her grandchildren were shot and killed in her home on Sunday afternoon. Police were called to the scene after Johnson's fourth grandchild escaped and called 911.

A possible suspect, a New Town man in his late 20s, killed himself hours later in Parshall, 20 miles away, police told the AP.

Mountrail County Sheriff Ken Halvorson, who did not identify the suspect, said he was in the process of being interviewed about the crime when he stabbed himself to death. Halvorson told the AP, "It happened in front of a deputy and a highway patrolman."

Johnson's husband was hunting at the time of the incident. The family were not enrolled Three Affiliated Tribe members but the man who committed suicide was, according to Halvorson. Because the shooting took place on an Indian reservation and because a suspect was a member of the Three Affiliated Tribes, the Mandan, Hidatsa and Arikara, the FBI is also taking part of the investigation along with the Bureau of Criminal Investigation and the Bureau of Indian Affairs, reports Inforum.

Speaking about the tragic shooting deaths, Three Affiliated Tribes Chairman Tex Hall said, "It's a terrible loss, especially when young kids are involved. It's a sad, sad day," reports AP.

Marc Bluestone, superintendent of the public school in New Town, canceled classes in the wake of the shooting, saying, "In the best interests of our community and school, with the limited information we have, my decision is to call off school for (today)," notes Inforum.

FBI spokesman Kyle Loven said, “We are confident there is no threat to the public at large." The FBI along with the BCI, BIA and Mountrail County Sheriff's Department are  investigating the shooting.