Five more people have died from overdoses related to the powerful drug carfentanil, bringing the total to 10 deaths in Minnesota, the Hennepin County medical examiner confirmed Friday.

“We remain vigilant and continue to order the carfen­tanil and designer-opioid testing on a case-by-case basis after considering the autopsy findings, investigation and laboratory results,” said Dr. Andrew Baker, county medical examiner.

Carfentanil, a powerful opioid new to the state, is said to be 10,000 times more potent than morphine and 100 times more potent than fentanyl, another synthetic opioid. It is intended as a tranquilizer for elephants and other large animals, and ingesting just two salt-sized grains can be fatal for humans, officials warn.

Routine drug screens do not detect the drug in humans, so samples must be sent to a specialized lab for testing.

Carfentanil, a white powder, is so powerful that it can harm police, medics and other first responders exposed to the drug. The substance can come in several forms, including powder, blotter paper, tablets, patches and spray. Some forms can be absorbed through the skin or accidentally inhaled.

Carfentanil can’t be diluted enough to make it safe for humans, said Ken Solek, the Drug Enforcement Administration’s assistant special agent in charge in Minnesota.

Baker said his office is still investigating a handful of other deaths to determine whether they were caused by carfentanil. Authorities haven’t determined if any of the deaths are connected or found the source of the drug.

The deaths occurred from January to March. Most were in Minneapolis; the others occurred in Apple Valley, Faribault, Plymouth, Maple Grove and Eden Prairie.

Baker said when the usual drugs didn’t appear in the 10 overdose deaths, his staff tested for novel drugs.

Solek said identifying carfentanil was a major step, but it left police scrambling for ways to stop the influx into Minnesota and to keep drug dealers from using it. Victims probably didn’t know that carfentanil had been laced into the heroin they purchased, authorities said.