OAKLAND PARK, Fla. -- The clinic where four patients went for wrinkle-smoothing treatments but ended up getting botulism has been secured as a crime scene.

Agents from the Food and Drug Administration's Office of Criminal Investigations obtained a search warrant to gather evidence.

Images: Botox Clinic Searched

State and federal health investigators said they did not know if the four patients were injected with Botox, another brand called Myoblock, or some other substance, such as a look-alike product made overseas and sold in America without federal approval.

Officials closed the Oakland Park clinic, Advanced Integrated Medical Center. The center employed a former physician, 47-year-old Bach McComb, who was one of the four hospitalized from the shots last week.

The state suspended McComb's medical license last year for improperly prescribing painkillers.

Botulism is a rare and potentially fatal paralytic illness that affects muscles, eyes, limbs and respiratory tract.

Botox is a derivative of the toxin that causes botulism and has been used as an anti-wrinkle drug. Some patients have been known to suffer serious, and even fatal, reactions.

Hospital officials and family members said the four were recovering in the hospital.