A refrigerant leak at a single unit in an apartment building near San Francisco’s Union Square prompted an emergency response from the San Francisco Fire Department on Sunday afternoon.

SFFD brought a hazmat team to the residence at 625 Bush St. around 4 p.m., the agency said on X, as KRON4 first reported. Three adults were treated for exposure to the leaked substance and have since been released from the care of SFFD medical teams.

The situation also caused disruptions in the busy area, leading to traffic delays along Bush Street between Powell and Stockton. SFFD urged the public to steer clear of the affected zone.

Authorities confirmed that the leak was an isolated incident and did not spread to neighboring units.

Refrigerant chemical leaks, usually from HVAC units or refrigerators, can be poisonous — they can cause headaches, coughing, respiratory trouble, dizziness, nausea, or even mild burns if skin gets direct contact. (The chemicals can also be flammable.)

Feature image via SFFD.