Nassau County officials are issuing a new warning about an online challenge in which people set themselves on fire and post the video to social media.

"Do not set yourself on fire," Nassau County Executive Ed Mangano said Tuesday as he issued a public health alert to parents about the "fire challenge" circulating social media.

Some of the videos depict people dousing themselves in alcohol, lighting themselves on fire and then jumping into a shower or pool of water.

Mangano was joined by physicians at Nassau University Medical Center, where a 12-year-old Far Rockaway boy was transported after a failed challenge attempt.

The boy suffered third-degree burns to about 40 percent of his body. Doctors say he's doing "relatively well" after undergoing reconstructive surgery.

Dr. Roy Aranda, a child psychologist in Hempstead, says the growth of social media and the increase in online access for young children helps fan the flames for stunts like the "fire challenge." He adds the behavior depicted can be curbed at home with the help of parents.

The incident involving the boy from Far Rockaway marked the first "fire challenge" case treated in Nassau County. Suffolk officials say they haven't received any reports of the social media stunt.