A huge police presence was in Runcorn town centre this morning as officers chased a man on foot through the streets.
At about 11.35am officers and an ambulance were called to Thomas Street.
One woman and four men were arrested on suspicion of possession with intent to supply Class A drugs.
As officers were called to the scene, one of the men suffered a "medical episode".
A spokeswoman for the North West Ambulance Service said an ambulance was called on reports of someone "fainting or feeling unwell."
They did not require hospital treatment, police added.
A witness, who asked not to be named, said: "I was on my front and I seen the police running down Dover Stret and then obviously a man had hopped over here onto Dover Street into my mate's back garden, down to The Deck and the police chased him.
"The Heddlu (Welsh firearms) police were here, the (BMW) X5s, and two others and the riot vans and about 10 undercover cars, all CIDs.
"My mate was cooking bacon and seen someone in his back garden and sprinted."
She added: "I've seen three vans come down here.
"One got stuck in my street."
All five people were taken to custody to be questioned, while an address on Thomas Street is searched by officers.
A spokeswoman for Cheshire Police said: "At around 11.35am officers arrested five people, one woman and four men, on suspicion of possession with intent to supply class A drugs on Thomas Street.
"A man ran away from the scene but was quickly detained nearby.
"Another man suffered a medical episode and was assisted by ambulance.
"He was not taken to hospital.
"All have been taken to custody to be questioned.
"An address on Thomas Street is being searched by officers."
