Northamptonshire's police chief says drivers are using the county's empty roads like a race track during the coronavirus lockdown.
And he warned the county's mobile speed cameras will still be out in force during the crisis.
Boris Johnson ordered the country to stay indoors on Monday night in a bid to slow the spread of the deadly Covid-19 bug.
But some are flouting the Prime Minister's plea to avoid all non-essential travel while others find the lack of traffic out on the roads too much of a temptation not to put their foot down.
Chief Constable Nick Adderley said: "With the roads being clearer, due to the Government restrictions, some feel this is licence to use them like a race track.
"Northamptonshire Police will still deploy its camera safety vehicles and will still robustly enforce the Road Traffic Act.
"Slow down and don’t add to the NHS demand."
Northamptonshire Police issued nearly 5,000 fixed penalty notices for speeding offences last month.