Drugs obtained illegally were the main killers of the 2,212 people who died of overdoses in 2013 and 2014 in Massachusetts, according to a report from state health officials issued Thursday.

Only 8.3 percent of those who died had a prescription for an opioid drug, while 85 percent had taken heroin or fentanyl. This finding shows that the drugs that kill usually come from the street.

Fulfilling a legislative mandate, the Massachusetts Department of Public Health analyzed its data along with data from other government agencies to produce the report, available online at the Massachusetts Department of Health and Human Services website.

The report also found that half of those who died had benzodiazepines in their system.

The popular tranquilizers exacerbate the effects of opioids on the central nervous system, making deaths more likely as breathing and heart rate slow.

Additionally, people who survived an overdose and then obtained treatment with drugs that tamp down cravings — such as methadone or Suboxone — were much less likely to die from another overdose. The report mentioned “a short window of opportunity’’ to bring an overdose survivor into life-saving treatment.

Other findings: Women who overdose are more likely than men to have taken a prescription opioid. And people newly released from prison are at great risk, 50 times more likely than the general public to die of an overdose.

Felice J. Freyer can be reached at felice.freyer@globe.com.