A female nurse was arrested on suspicion of murder Wednesday in connection with three deaths at a British hospital, Sky News reported, citing sources.

The arrest of the 26-year-old member of staff came as it was reported that contaminated saline was also discovered on the maternity ward at Stepping Hill Hospital in Stockport, northwestern England.

Altogether, 14 patients at the hospital were given saline solution that had been deliberately contaminated with insulin.

Tracey Arden, 44, Arnold Lancaster, 71, and George Keep, 84, died, and another patient, an unnamed man in his 40s, is in critical condition.

The 10 other patients who were affected by the tampered medication recovered, including one woman who had a seizure after the contaminated saline was directly injected into a drip she was hooked up to.

A statement from Greater Manchester Police said, "This morning, Wednesday 20 July 2011, a 26-year-old woman was arrested on suspicion of murder. She remains in police custody for questioning."

Police said they are carrying out tests to find out whether the saline container found on the hospital's maternity ward was deliberately contaminated or was damaged accidentally.

Assistant Chief Constable Ian Hopkins said Tuesday, "We are dealing with somebody who is committed to causing injury and someone who may try to find all sorts of ways to get around the security measures. We have not had any further incidents since the measures were put in place. Our primary aim is to prevent any further harm. Our next priority is to catch the person who has done this."

Medics at the hospital were being made to work in pairs after health chiefs called for staff to keep an eye on each other's work and also increased security at the unit.

The alarm was first raised July 12, after multiple sclerosis sufferer Arden died July 7. The two male victims, who both had serious health problems, died last week.

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