A senior West Midlands Police officer is on a ventilator with Covid-19 symptoms.
Ch Supt Phil Dolby is being treated in an intensive care unit, colleagues said, after becoming unwell just over a week ago.
Mr Dolby, who is in charge of the force's criminal justice services, has posted Twitter updates.
On Sunday, he posted a video showing his surroundings, having been admitted to a hospital isolation ward.
Updating people on Mr Dolby's condition, colleagues said: "He is currently in an ITU on a ventilator and is being looked after by the amazing NHSuk.
"Positive thoughts and prayers for him please. COVID19."
A force spokeswoman said Assistant Chief Constable Chris Johnson had been in continuous contact with Mr Dolby's wife and family who are asking friends and colleagues "to keep Phil in their thoughts and to pray for him".
West Midlands Police has more than 1,000 officers and staff off work or unable to carry out normal duties because of sickness or self-isolation, a senior national policing source said.
There are about 6,500 officers and 3,000 staff at the force - the largest outside London's Met.
Mr Dolby posted social media updates on his condition at the weekend.
He talked of enduring "some frightening episodes of breathlessness and dizziness".
"111 called an ambo. Conveyed to hospital," he added.
"Now got oxygen mask, canulars, blood test, Covid tests, chest x-ray and some snory neighbours."
His chief constable Dave Thompson responded saying: "Get well, Phil."
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