Washington (CNN) -- Seven midshipmen were expelled from the Naval Academy for using a drug called "spice" in violation of the Navy's policies on illicit substance abuse, officials said.
The midshipmen were "separated from the Naval Academy" as of Thursday, said Cmdr. Joe Carpenter, spokesman for the academy.
"While we will not go into the details of individual cases, the violations of the Navy's substance abuse policies included use and possession," Carpenter said in a statement. "These cases involved 'spice,' which is considered a banned substance by the departments of Defense and Navy."
"Spice," also known as K2, is a mixture of herbs and spices that typically is sprayed with a synthetic compound chemically similar to THC, the psychoactive ingredient in marijuana, according to a Drug Enforcement Administration fact sheet.
"K2 is commonly purchased in head shops, tobacco shops, various retail outlets and over the Internet," the DEA said. "It is often marketed as incense or 'fake weed.'" Its effects on the body are similar to that of marijuana.
The midshipmen included juniors and sophomores, Carpenter said. The academy, located in Annapolis, Maryland, did not identify them.
On whether they will have to repay the cost of their education, Carpenter said the decision is up to the Department of the Navy.
"Consistent with Navy policy, the Naval Academy has a zero tolerance policy regarding illicit drug use or possession," Carpenter said. The investigation is ongoing, he said.
Other midshipmen told academy leadership about the allegations after the fall semester began, he said.
In 2009, 11 midshipmen were found to be in violation of the Navy's substance abuse policy. In 2010, four other midshipmen were found to be in violation.
Spice is usually smoked in joints or pipes, according to the DEA, but some users make it into a tea. Its key ingredients are not regulated in the United States, but they have been banned or declared illegal in some European countries. The U.S. military has banned their use, the DEA noted.
CNN's Adam Levine contributed to this report.