Multiple defense officials have told CNN that the National Guard and law enforcement expect explosives like pipe bombs and Molotov cocktails to be used in any coming unrest. They are assuming perpetrators will come with high “aggression,” said one senior defense official, who added, “their intentions are very serious.”

Pipe bombs that could have done serious damage were planted outside the Republican and Democratic party headquarters in Washington last week but didn’t go off.

The expertise behind the bombs and the ease with which the raucous crowd seemed to mill about the Capitol complex with little resistance raised concerns participants had insider help and military expertise.

At least two US Capitol Police officers were suspended and at least 10 more are under investigation for allegedly playing some sort of role, CNN reported. Michael Sherwin, the acting US attorney in Washington, DC, confirmed Friday that “we’re seeing indications that law enforcement officers, both former and current, maybe who have been off duty, participating in this riot activity.”