GRAND RAPIDS, Mich. (AP) — Prosecutors added charges Wednesday against three of six people accused of plotting to kidnap Michigan Gov. Gretchen Whitmer.

Adam Fox, Barry Croft Jr. and Daniel Harris conspired to use a weapon of mass destruction, namely a plan to blow up a bridge near Whitmer’s second home in northern Michigan to hinder police, according to an expanded indictment filed in federal court in Grand Rapids.

The role of the bridge in the alleged plot was disclosed by authorities months ago.

Croft and Harris also were charged with possession of an unregistered destructive device. Harris also faces a new charge of possession of an unregistered short-barreled rifle.

The three men, along with Kaleb Franks and Brandon Caserta, were arrested in October and indicted on a kidnapping conspiracy charge. They have pleaded not guilty. A sixth man, Ty Garbin, pleaded guilty in January.

The FBI said it broke up a plot to kidnap Whitmer, a Democrat, by anti-government extremists upset over coronavirus restrictions she had imposed in Michigan. A separate group has been charged in state court with aiding them.