Officials are investigating a batch of "spice" linked to cases of kidney failure. Image credit: Wyoming Division of Criminal Investigation

Health officials in Casper, Wyo., are investigating an outbreak of kidney failure linked to a batch of synthetic marijuana known as "spice."

Three people were hospitalized Friday and two more were treated and released from a hospital in the eastern Wyoming city of 55,000 residents.

The patients, all in their teens and early 20s, reported vomiting, back pain and stomach pain. Officials are investigating reports of two others who reported similar symptoms earlier in the week.

Bob Harrington, director of the Casper-Natrona County Health Department said the cause of the outbreak was still under investigation, but all of the people who were sickened reported smoking or ingesting blueberry-flavored spice.

Scientists at the Wyoming State Crime Laboratory are investigating the chemicals used in the batch of spice implicated in the illnesses. On Thursday, the Wyoming Department of Health issued a warning to health care providers around the state, alerting them to the potential connection between the drug and the reported symptoms.

"At this point, we are viewing use of this drug as a potentially life-threatening situation," Dr. Tracy Murphy, the state epidemiologist for the Wyoming Department of Health, said in a statement.

Spice, also known as K2, skunk and moon rocks, is made of plant material laced with chemicals that mimic the effects of THC, the active ingredient in marijuana.

According to the National Institute on Drug Abuse, spice is often marketed to people interested in an alternative to marijuana.

The drug has a range of potentially dangerous effects, including soaring heart rate, elevated blood pressure, vomiting, paranoia, convulsions and hallucinations. In 2010, an Iowa teenager committed suicide shortly after smoking spice.

Although it's often called "legal marijuana," several states, including Wyoming, are cracking down on the drug and the chemicals used to make it.  And on Wednesday, the U.S. Drug Enforcement Administration extended a ban on five chemicals commonly used to make spice, citing the need to "prevent an imminent threat to public health and safety," according to a statement on the DEA website. The action extends a ban on selling or using these chemicals for an additional six months as a permanent ban is considered.

But manufacturers often get around such roadblocks by tweaking spice recipes to swap banned chemicals for alternatives, thereby skirting laws aimed at prohibiting the drug. The drug is usually sold in head shops, certain retail stores and over the Internet.

The use of spice has been on the rise in recent years, particularly among teens and young adults. A 2011 report from the National Institute on Drug Abuse found that 11 percent of seniors in high school reported trying spice in the past year. In the same survey, a third of all 12 th graders reported trying marijuana.