Anti-vaccine protesters on Friday hurled what authorities believed to be blood onto the Senate floor at the California State Capitol in Sacramento, leading to an evacuation of the building on the final day of the legislative calendar.

A video of the incident was posted on social media, which shows a woman telling California Highway Patrol officers, "My menstrual blood is all over the Senate floor." The woman was subsequently detained, and posts from her Twitter account are connected to anti-vaccine demonstrations that occurred at the Capitol earlier that day.

"A few minutes ago, the anti-vaxxer stalkers - who’ve engaged in a harassment campaign all week - dropped a red substance onto the Senate floor from the elevated public gallery, dousing several of my colleagues," state Sen. Scott Wiener tweeted. "The person who committed this assault screamed it was baby blood."

1/2 A few minutes ago, the anti-vaxxer stalkers - who’ve engaged in a harassment campaign all week - dropped a red substance onto the Senate floor from the elevated public gallery, dousing several of my colleagues. The person who committed this assault screamed it was baby blood. — Scott Wiener (@Scott_Wiener) September 14, 2019

Numerous lawmakers were hit by the red liquid, which was thrown from the upstairs balcony by protesters who were reportedly watching the floor debate at the time. They had objected to two pieces of legislation signed into law earlier in the week that would place strict regulations on medical exemptions for childhood vaccines.

CHP officers evacuated the chamber and opened an investigation into the incident, which allegedly happened at 5:14 p.m. Officers rolled out crime scene tape around the area, and CHP announced it had detained the protester on six charges after she "threw a feminine hygiene device containing what appeared to be blood onto the Senate floor."

Friday was the last night of session, and lawmakers were on a tight deadline to send legislation to Gov. Gavin Newsom before adjourning. The Assembly returned to session just after 7:30 p.m., and the Senate was forced to reconvene at 8:45 p.m. in its biggest committee room because the chamber was still a crime scene.

The incident marked the first time since 2001 that the Senate did not convene in its own chamber, when a man drove a semitruck into the southern part of the Capitol building.