Paramedics were called to the location at around 3:00 PM on Wednesday afternoon.

Seven fire engines and hazardous material officers, along with a specialist chemical unit are also at the scene.

A spokesperson for the Kent police said officers responded to "reports of a suspected chemical leak" after being contacted by the ambulance service, the BBC reported.

In an update posted online, Kent Fire and Rescue Service said it had deployed more than 40 firefighters to the scene. Crews are wearing breathing apparatus and trying to decipher what the chemical is, they said, adding that the chemical "is contained to the site."

One witness told the Daily Express that emergency responders descended on Maidstone Hospital in what looked like a "full-scale operation."

“Nobody is being allowed into the hospital and big white hazard tents have been set up outside," the man said.

Reports suggest that the incident took place on a fruit-picking farm and that those affected are foreign nationals in their 20s and 30s. It is believed that the victims were overcome by carbon monoxide – an odorless and tasteless gas – and began having trouble breathing.