PHILADELPHIA (KYW Newsradio) — The Department of Homeland Security is investigating after someone threw a chemical mixture into a West Philadelphia police building Friday night, causing officers to evacuate.

The incident happened around 9:15 p.m. Friday. Police said someone released a chemical mixture in the witness waiting area of the Southwest Detectives Division at 55th and Pine streets.
Several officers started coughing and experiencing burning eyes.
A hazmat incident was declared and the building was evacuated while the Philadelphia Fire Department, Department of License & Inspection, Office of Emergency Management and Homeland Security investigated. The building has since been cleaned and cleared for return.
According to officials, the mixture could be a combination of mace and another unknown substance. They are still trying to determine who was responsible for the incident.
No injuries were reported and no civilians were inside the waiting room at the time of the event.