Chief Sund did not hear back for 61 minutes after he called for help from the National Guard. And even then, there was a catch: Though Capitol security officials had approved his request, the Pentagon had the final say. During a tense phone call that began 18 minutes later, a top general said that he did not like the “visual” of the military guarding the Capitol and that he would recommend the Army secretary deny the request.

Pentagon approval finally came at 3:04 p.m. The first deployment of National Guard troops arrived at the Capitol two and a half hours later.

Video evidence and interviews show the Capitol Police and supporting police units were overwhelmed for several hours after the first members of the pro-Trump mob breached the outer perimeter of the complex.

One snapshot of the violence: At 4:25 p.m., rioters outside the Capitol building beat police officers using American flags. Two minutes later, a mob outside the House chamber dragged the first of two officers from the city’s Metropolitan Police down a flight of stairs. Elsewhere, on the Capitol grounds, one protester who collapsed in the crush of bodies was trampled by the mob. She was later pronounced dead.