The nerve agent Novichok has poisoned two new victims in England, The Telegraph reports. The two collapsed after visiting Salisbury, the same town where former Russian double-agent Sergei Skripal and his daughter Yulia were attacked with the chemical weapon back in March.

A man and a woman in their 40s, identified by The Telegraph as Charles Rowley and Dawn Sturgess, were rushed to the hospital on Saturday after they passed out at a home in Amesbury, according to a televised police statement. A witness told The Telegraph that both were foaming at the mouth — a sign of nerve-agent poisoning.

At first, doctors thought contaminated drugs were to blame. But by Monday July 2nd, doctors were concerned enough about the patients’ symptoms that they sent samples to defense laboratory Porton Down for testing. Those tests revealed that the couple had been poisoned by Novichok, authorities announced today.

The term Novichok actually represents a collection of nerve agents developed by the Soviet Union towards the end of the Cold War. Like other nerve agents, they work by glomming onto an enzyme that’s key for healthy signaling between nerves and muscles — leading to drooling, seizures, and paralysis. “So, it’s a horrible way to die,” Peter Chai, a medical toxicologist at Brigham and Women’s Hospital in Boston, told The Verge in March. Novichok agents are also thought to directly damage nerves, according to a paper Chai recently published in the journal Toxicology Communications.

That’s why prompt treatment is so important — and knowing that a nerve agent is to blame will help. Treatment will likely include drugs to dry out the patients’ secretions and seizure medication. That deals with the immediate symptoms, while another drug works to pry the nerve agent off that key enzyme. For now, the patients are still in critical condition, according to the BBC.

The good news is that the Skripals have recovered. The bad news is that these new Novichok cases suggest that there may still be Novichok in Salisbury, despite efforts to decontaminate the area. Nerve agents don’t just poison people — they stick around and poison the land, making the attack even scarier. “They’re really oily so they persist in the environment,” Chai told The Verge in March. “So the intention is to use them in an area where people just can’t go into the land anymore, so you’re denying territory.”

We still don’t know if, or how, the two attacks are connected. But unlike the Skripals, Rowley and Sturgess probably weren’t the victims of a targeted attack with the chemical weapon, the BBC reports. Instead, they may have been poisoned by touching something that became contaminated with Novichok during the assassination attempt on the Skripals, Deborah Haynes, the defense editor for The Times, posted on Twitter.

It’s a logical hypothesis, tweets Dan Kaszeta, an independent security consultant and chemical weapons expert: “After all, nerve agents are indiscriminate weapons and the Novichoks were engineered with persistent contamination of land and equipment in mind.”