The number of road traffic deaths involving police in England and Wales increased by more than 50% in the past year, the latest figures show.
The Independent Police Complaints Commission said fatalities in police road traffic incidents rose by 11 to 32 - the biggest total in eight years.
Twenty-eight of the road deaths were related to police pursuits of vehicles.
The figures also reveal there were six fatal police shootings from April 2016 to March 2017, from three in 2015-16.
The six shootings - including that of Westminster attacker Khalid Masood - is the highest number in 12 years.
Dame Anne Owers, chairwoman of the IPCC, said the National Police Chiefs' Council and the IPCC would examine whether changes to police pursuit safety or training were needed after the rise in road traffic deaths.
But the Police Federation, which represents rank-and-file officers, blamed the increase in deaths on cuts to road traffic policing.
"Since 2000, the number of roads policing officers has almost halved, with less than 4,000 now working across England and Wales," a spokesperson for the staff association said.
"Unfortunately this could mean a higher proportion of fatalities or serious injuries."
By Danny Shaw, BBC home affairs correspondent
Since the IPCC was set up in 2004, there have never been more than a handful of fatal police shootings in a year, so the fact there have been six is unlikely to raise alarm bells.
And, as the watchdog points out, the number has to be set in context: there were more than 14,700 police firearms operations during the same 12-month period - the vast majority pass off without a shot being fired, let alone anyone dying.
However, the sharp rise in pursuit-related deaths - after a concerted effort by police and the IPCC to reduce the number of such casualties - will prompt searching questions. Of the 28 who died, 18 were either passengers in the suspect vehicle or other road users.
Does the rise simply reflect an upsurge in criminal activity? Is it because suspects have become increasingly reckless? Or have police standards on the roads slipped?
The IPCC and the National Police Chiefs' Council will have to get to the bottom of it quickly.
Dame Anne said the six fatal shootings had occurred across six forces and that the shooting of Khalid Masood was the only one related to terrorism.
The watchdog said the investigation into that case and two others had been completed and all three had found no evidence of any misconduct by firearms officers.
In addition, another inquiry, which is still ongoing, is also yet to find any evidence of wrongdoing by police.
Investigations into two other shootings are still to conclude.
The IPPC data also showed there were 14 deaths in police custody - the second lowest figure it has recorded.
Eight of the 14 people who died were reported to have mental health problems.
Dame Anne said that many of those who died in custody, or shortly after their release, were "vulnerable" but that police needed support to help individuals.
Deborah Coles, director of Inquest, the charity concerned with deaths in custody, said the figures were a "depressing picture" of the treatment of detained people.
She said: "While the police cannot and should not be the default service responsible for those with mental and physical health concerns, where they are called to act they must do so with care and dignity."
A recent independent report, also using IPCC data, said there were 400 "apparent suicides" of people who had been detained at police stations during the seven years to March 2016.
The Equality and Human Rights Commission, which produced the report, blamed many of these suicides on "serious gaps" in the care of detained people.