CHICAGO (Reuters) - Four people have been indicted on arson charges in a fire that damaged a Michigan State University building, a 1999 blaze for which environmental activists claimed responsibility, officials said on Tuesday.

“This was a significant act of domestic terrorism which caused more than a million dollars in damage to facilities and loss of research records,” the university’s police chief, James Dunlap, said in a report issued by the school.

The 1999 fire at Agriculture Hall damaged the office of the Agriculture Biotechnology Support Project, which the school said works to promote agricultural biotechnology in developing countries.

“Shortly after the fire a loosely organized environmental movement called the Earth Liberation Front claimed responsibility,” the announcement said.

The shadowy band of radical environmental activists has been blamed for several arsons in the U.S. Pacific Northwest in recent years and designated by the FBI as “eco-terrorists.”

Indicted by a federal grand jury on charges of arson, aggravated arson, and conspiracy to commit arson were Marie Mason, 46, of Cincinnati; Frank Ambrose, 33, Aren Burthwick, 27, and Stephanie Fultz, 27, all of Detroit, the FBI said.

Earlier this month, a hand-painted sign with the group’s initials was posted near a fire that destroyed three luxury homes in a Seattle suburb, which the sign denounced as “McMansions,” a derisive term for large homes often in rural developments.