Anti-coronavirus protests: How safe is the German parliament?

Aggressive demonstrators penetrated the Bundestag while parliamentarians were discussing the new Infection Protection Law, expanding government powers in the anti-coronavirus crisis. How was this disruption possible?

source https://www.dw.com/en/anti-coronavirus-protests-how-safe-is-the-german-parliament/a-55666129?maca=en-rss-en-ger-1023-rdf