A man and woman were found dead Monday afternoon in an apartment in Sheepshead Bay after an apparent double suicide.
EMS was called to the scene on Emmons Avenue at around 12:45 p.m.
First responders found the bodies of a 43-year-old man and a 44-year-old woman.
Investigators said a suspicious substance was found on a table near the victims' bodies. The city Department of Environmental Protection was called and determined that the substance was cyanide.
Cyanide is a highly toxic chemical that, when ingested, rapidly affects the body and can cause death within minutes.
Portions of the apartment building were evacuated as a safety precaution. Tenants have since returned.
According to police, nine officers were exposed to the cyanide while responding to this apartment. Those officers have not shown any adverse reactions.
The identity of the victims has not yet been released.