(Huffington Post) – U.S. Park Police radio recordings show that officers were overwhelmed by Donald Trump-supporting mobs in Washington hours before the violent breach of the Capitol on Jan. 6.

Even before Trump whipped the crowd into a frenzy at a pre-riot rally on the National Mall, cops radioed that they were overwhelmed by mobs and by people they suspected were armed at the Lincoln Memorial and Washington Monument, and were unable to check numerous unattended bags for bombs or weapons. Hours later, pipe bombs were discovered in similar bags in front of the Republican and Democratic national committee headquarters.

The recordings, obtained Thursday by the watchdog group Citizens for Responsibility and Ethics in Washington, renew questions of why law enforcement was so unprepared for the violence at the Capitol building hours later. The recordings also contrast the stunning lack of preparedness on Jan. 6 with the violent law enforcement response to peaceful Black Lives Matter protesters in nearby Lafayette Square months earlier to make way for Trump to pose with a Bible in front of a church.

Seven hours of recordings “make it abundantly clear that [the Park Police were] unprepared for the threat of a riot, lacking manpower, plans and supplies,” the watchdog group said in a statement.

“People are refusing to leave,” said one radio caller early on at the Washington Monument, where officers were later forced to hunker down as they were surrounded by the angry crowd. “The only other thing I can think I can do is threaten arrest which is gonna incite the crowd, so unless we get some officers up here I’m gonna stand by,” the officer added.

Another soon reported: “Units are backed into the monument, everyone’s breaking through the bike racks.”

Another called in: “We’re not going to be able to hold that base and that fence line with the numbers we have.”

Soon cops were ordered to “monitor only.”

“Copy,” an officer responded. “We don’t have the full react squad coming up, we’re not gonna agitate them.”

At one point, shortly before Trump spoke to the crowd and told them to march on the Capitol, one officer radioed: “Possible several individuals on the southwest quadrant of WaMo grounds that may be armed.”

One call announced the beginning of the day’s true nightmare: “The Capitol has been breached. Protestors have entered the building.”

Officers were so outnumbered by then that police couldn’t even risk making arrests when an officer was attacked with a pipe.

“We cannot afford to lose the personnel up here,” said a person on one of the calls.