Authorities say deputies were working with Pasadena Police detectives in a joint investigation.
The suspects collided into the deputies' vehicle without notice around 12:20 p.m. Thursday. The suspects got out of the car and fled, and at least one suspect fired at the deputies.
Deputies returned fire, but it was unknown if the suspects were hit. No officers were injured.
A large containment was immediately set up, but after eight hours of searching with dogs and helicopters, the search was called off.
The suspects were both described as male black, 18 to 25 years of age, thin build, wearing a black T-shirt and blue jeans.
The incident remains under investigation. Anyone with information is urged to call the Pasadena Police Department at (626) 744-4241 or the Los Angeles County Sheriff's Department at (323) 890-5500.