2:13 p.m. Senate members take cover in various parts of the Capitol building

Around 2:13 p.m., the Senate meeting about Electoral College votes abruptly goes into recess when they find out that there are protesters in the building. As the police clashed with the protesters, some Congress members were able to evacuate the building, while others were trapped inside. 

Source: https://www.nytimes.com/interactive/2021/01/12/us/capitol-mob-timeline.html