SAN FRANCISCO—San Francisco police are asking for the public’s help to identify several suspects responsible for a chemical attack on two officers. The incident occurred on November 3 during a protest at the United Nations Plaza.

A planned free speech rally met early in the afternoon on November 3, and gathered in the United Nations Plaza in downtown San Francisco. This was the second free-speech rally that has been held in San Francisco over the last month. The rally’s purpose was to defend the right of free-speech amid Election Day. Shortly after the protest formed, opposing demonstrators also gathered and begin to knock down barricades.

“Within minutes of the rally beginning, opposition demonstrators began throwing glass bottles, plastic bottles filled with an unknown liquid, metal cans, and eggs at free speech rally participants and law enforcement personnel”, a news release from the San Francisco Police Department (SFPD) stated.

In a statement, the SFPD said “the rally became so violent in nature it was declared a public safety hazard and was shut down.”

The incident reached its peak when several free-speech protesters were seriously injured, and two officers were also injured after suspects threw what was described as “caustic chemicals” at them. Police said those chemicals became “airborne” after they were thrown, and the officers experienced serious side-effects such as temporary blindness, trouble breathing, and “burning in their lungs, throat and on their skin”, the release described.

Police called in the San Francisco Department of Public Health to conduct an analysis of the type of liquid that was thrown. Health officials found a mixture of several chemicals, some of them known to cause “neurological harm, eye and skin irritation, headaches, dizziness, nausea, vomiting, and chemical burns”, said police in a statement.

Under California law, assaulting a police officer is a misdemeanor punishable by up to one year in county jail plus a fine of up to $2000. No arrests have been made yet in connection with the assault on officers. Police continue to investigate, and anyone with any information on the suspects is asked to call the 24-hour Anonymous Tip Line at 415 575 4444.