The red liquid that an anti-vaccine protester flung onto California state lawmakers during a legislative session September 13 was, in fact, human blood, lab tests confirmed.

The woman—identified as Rebecca Dalelio, 43—tossed the blood from the visitor’s gallery of the Senate chamber in protest of two bills tightening regulations of medical vaccine exemptions , according to reports by the Los Angeles Times . Gov. Gavin Newsom signed the bills into law September 10.

Dalelio was one of dozens of anti-vaccine protesters in the chamber on the 13th. Others had been seated quietly with their fists raised for more than an hour before the incident. A Facebook profile matching Dalelio contained multiple anti-vaccine postings, the Times noted.

As Dalelio showered the chamber with blood, the Senators were voting on a bill related to sexual harassment. Someone was heard yelling “this is for dead babies” at the time.

The California Highway Patrol quickly arrested Dalelio. In a later statement, the CHP said that the blood-like substance she threw had been contained in “a feminine hygiene device,” which witnesses described as a menstrual cup. Dalelio was booked into Sacramento County Jail on six charges including assault, vandalism, and disorderly conduct. She was released the next morning.

Meanwhile, authorities roped off the contaminated area, and lawmakers reconvened in a nearby committee room. The Senate gallery and floor have been closed ever since.

State Sen. Richard Pan (D-Sacramento), who wrote the two bills on vaccine exemptions, said that blood landed on his desk and back as well as other lawmakers’ heads.

It’s not the first time Dr. Pan has been the target of anti-vaccine protesters. In August, a prominent anti-vaccine advocate named Kenneth Austin Bennett livestreamed his assault on Pan as they encountered each other on a sidewalk near the state capitol.

“Everyone is pretty disturbed and upset,” Pan said after Dalelio’s attack. “It’s like we’ve been saying: violent rhetoric turns to violent acts. This is a direct attack on the democratic process, and this should be condemned by everyone. This needs to stop.”

In a document sent to lawmakers Wednesday, Secretary of the Senate Erika Contreras reported that “lab tests confirmed that the substance thrown from the Senate gallery was human blood.” She added that it tested negative for any bloodborne pathogens and infections.

Contreras also reported that the Senate chamber had been thoroughly sanitized and confirmed clean by a company certified in hazardous cleanups. It reopened Wednesday.