Police Chief James G. Downes III says that an antidote to overdoses of heroin or other opiates is now being carried on the town’s police cruisers as a life-saving measure. “We see the clear danger to life and safety presented by the opioid problem that has swept the nation,’’ Downes said. “As police, we have to attack this crisis from multiple fronts. We need to find and target suppliers, treat addiction, and prevent the loss of life, and as police officers, we are usually the first ones on the scene of an overdose. Now, we can do something about it.’’ The department’s officers were trained in how to administer nasal naloxone, also known as Narcan, by the Middlesex district attorney’s office.