HARTFORD, Connecticut — Eleven members of a police SWAT team became ill during a Connecticut drug bust after bursting into a Hartford apartment and finding themselves in a cloud of suspected drug particles, authorities say.

Police believe the officers were sickened in the Tuesday bust by airborne particles of the powerful painkiller fentanyl or heroin, or both.

The officers were released from a hospital after being treated for symptoms including nausea, light-headedness, sore throat and headaches, Deputy Police Chief Brian Foley said.

Police across the country have been warned about the dangers of fentanyl, which has been blamed for thousands of overdose deaths. A small amount of fentanyl can be deadly, and it can be inhaled or absorbed through the skin when it becomes airborne.

While no police deaths from fentanyl exposure have been reported, officers have become ill in several states.

“On a national level, it’s coming out through all the channels that this is a risk,” Foley said about fentanyl. “We’re just extra cautious as it’s more potent and dangerous than heroin.”

Hartford officers seized 50,000 bags of heroin, three-quarters of a pound of raw heroin, fentanyl, two handguns and drug packaging materials. Three people were arrested. Powder found on a table tested positive for both fentanyl and heroin, Foley said.

It wasn’t clear how the drug powder became airborne. Foley said it could be because officers fired stun grenades into the apartment while serving a search warrant, or the suspects were trying to clean it off the table before police barged in.

Law enforcement officials say drugs including heroin, cocaine and counterfeit prescription pills are now commonly laced with fentanyl to increase potency, and fentanyl is increasingly being sold by itself.

In June, the federal Drug Enforcement Administration released a video to law enforcement nationwide about the dangers of fentanyl to officers, including improper handling. The powerful drug is making police departments change how they operate, authorities say.