Dozens of people died following contact with Lancashire Constabulary in the past five years
It comes as police watchdog the Independent Office for Police Conduct said there is a 'clear over-reliance' on police officers as first responders in dealing with vulnerable people in crisis.
Figures from the IOPC show there were 25 deaths following contact with Lancashire Constabulary in the past five years – with four recorded last year.
Of the deaths in the past five years, one happened in or following police custody and three were the result of road traffic accidents involving police.
The figures also show five were apparent suicides and a further 16 deaths involving Lancashire Police during other incidents that the IOPC investigated – which can include police helping medical staff to restrain someone, or if officers are called to an incident that ultimately results in a fatality.
IOPC acting director-general Tom Whiting said he is not alone in calling for action across agencies to help prevent these deaths, especially in cases of vulnerable people who need of specialist care.
He added: "It is clear there is an over-reliance on the police service as first responders in dealing with vulnerable people in crisis.
"Police chiefs have expressed understandable concern about the heavy demand placed on their resources in dealing with mental health incidents."
Across England and Wales, the number of deaths in or following police custody jumped from 11 in 2021-22 to 23 last year. It is the highest figure since 2017-18.
They are among a total of 196 deaths involving police last year, which also include 52 apparent suicides, three fatal shootings, and 28 deaths from road traffic accidents.
Inquest, a charity which analyses state-related deaths, said many of these deaths are preventable.
Lucy Mckay, spokesperson for the charity, said: "We know from our work with bereaved families that so many of these deaths are preventable, both at the point of death and long before things reached a crisis point.
"Inquests and investigations uncover issues of institutional racism, disproportionate use of force, and neglect of people in need of care, not custody.
"Ultimately to prevent further deaths and harm, we must look beyond policing and redirect resources into community, health, welfare and specialist services."
Deputy Chief Constable Nev Kemp, National Police Chiefs' Council lead for custody, said every death is a tragedy and is fully investigated and scrutinised.
He added: "Police custody plays a pivotal role in keeping the public safe and supporting the criminal justice process.
"It is an exceptionally challenging and high-risk environment where dedicated officers and staff care for some of the most vulnerable and challenging people in society."
He said a new national partnership agreement signed this week will roll out a new approach for police forces in dealing with health incidents where policing is not always the best agency to respond.
"Police officers and staff are highly trained and committed but they are not health care professionals and are not the best people to deal with those in mental health crisis," he added.