In the weeks before the explosion, the operator of a medical marijuana delivery service in Phoenix, Arizona, had posted a video on Facebook showing a robot injecting patients into a plastic tube.
The video, taken from a drone, showed the robot filling a syringe with a green liquid and then pumping it into a patient.
The delivery machine exploded.
It was the latest in a string of deadly accidents in recent years involving injection machines and their makers.
The machines are the subject of a $25 billion class-action lawsuit filed by the federal government, which alleges the machines are not safe, can cause serious health risks, and are dangerous to the public.
The U.S. Food and Drug Administration has been cracking down on the industry, which has grown from $10 billion in sales in 2009 to more than $50 billion in 2018.
The industry, however, has not been immune to lawsuits.
Earlier this month, a federal jury awarded $2.2 million to a woman who was injured in an injection machine explosion in Chicago in 2013.
In the first year of the opioid crisis, the number of injection-drug-related deaths rose dramatically.
In 2016, there were more than 1,000 people dying each day, according to the Centers for Disease Control and Prevention.
According to the Justice Department, injection-machine manufacturers say the devices are safer than other types of medical devices and are designed to deliver drugs more quickly.
But in recent months, the industry has faced increasing scrutiny from lawmakers, consumer advocates, the Justice, Health and Human Services departments and even some states that have banned the machines.
The federal government has taken action against the industry over the past several months, including cracking down heavily on medical-marijuana companies that supply them with their products and requiring manufacturers to test the products for harmful chemicals.