FBI spokeswoman Laura Eimiller says a chemical reaction caused the explosion Sunday evening in an employee bathroom in Terminal 2.
No injuries were reported, but as a precaution authorities closed the terminal and examined the area for evidence.
Eimiller said the bathroom was in a restricted area of the terminal that was not accessible to the public.
Airport police Sgt. Karla Ortiz said officials temporarily halted security screening, which led to the delay of up to four departing flights.
Investigators were trying to determine how the bottle wound up in the bathroom.