A British nurse was arrested Tuesday for allegedly murdering eight newborns and trying to kill six others in a UK hospital’s neonatal unit, according to reports.

Lucy Letby, 28, allegedly engaged in the killing spree at Countess of Chester Hospital in Chester, England.

Letby wasn’t named by police but she was identified in news reports in the UK.

She is in custody on suspicion of murder and attempted murder charges but hasn’t been formally charged.

Letby’s arrest shocked friends and co-workers, who said she was devoted to the job and the infants in her care.

One friend, Jordan Sands, who knows Letby through a former girlfriend, told the Times of London, “She was quite awkward and geeky but seemed like a kindhearted person.”

Another called Letby “an amazing person.”

Letby was also active in a $4 million fundraising campaign to build a new neo­natal unit at the hospital.

“I hope the new unit will provide a greater degree of privacy and space,” she told the Chester & District Standard in supporting the campaign.

The 680-bed hospital in Chester, southeast of Liverpool, asked police in May 2017 to investigate a sudden, unexplained mortality-rate spike in the unit that houses premature babies and those needing special care.

When doctors couldn’t determine how they died, the police were asked to rule out “unnatural causes of death.”

The probe initially focused on the deaths of eight babies, but authorities said Tuesday it now includes the deaths of 17 and 15 “nonfatal collapses” between March 2015 and July 2016.

A “nonfatal collapse” is when an infant’s health severely declines but the child survives.

“Whilst this is a significant step forward in our inquiries it is important to remember that the investigation is very much active and ongoing at this stage,” said Detective Inspector Paul Hughes.

The grisly case involves parents from Cheshire and the north Wales area. Hughes said they’ve been notified and are being updated on the investigation.

“At the heart of this, there are a number of bereaved families seeking answers as to what happened to their children,” he said.

Countess of Chester Hospital cares for some 400 infants in its neonatal unit annually.

Additional reporting by David K. Li