The first man died as a result of taking the Class A drug on Friday and a second man, who had been admitted to hospital earlier, died on Saturday night.

Devon and Cornwall Police said his death is believed to be as a result of taking the same batch, which is thought to be a "form of heroin combined with another substance" which causes "more serious effects" than regular supplies.

A total of 10 people, including the man who died, have been treated in hospital. Two are still being treated.

Two men and two women arrested on suspicion of being involved in the supply of a controlled substance have been released on police bail pending further inquiries.

What was "locally thought to be an unusual batch of heroin" circulating in Westward Ho!, Bideford and Barnstaple became known to officers and partner agencies at 5pm on Friday, police said.

A major incident was declared, before being stood down on Saturday morning.

"We believe the substance found on Friday has been contained," said Detective Superintendent Ben Davies.

He added: "While we believe there is no threat to the wider community, we continue to investigate the circumstances of the now two deaths as a result of taking this substance.

"We are continuing to carry out tests in order to ascertain what the substance is, but suspect it is a form of heroin combined with another substance which users will find causes more serious effects than heroin which they might usually use."

Health workers are working with local drug users to "safeguard them as much as possible", he said.

Users are urged to "exercise extreme caution", he added.

"Advice remains that if you feel you are suffering an adverse reaction or are in the company of someone in need of urgent medical attention, call 999 for appropriate care and help."