At least 45 drain and gully covers were stolen from roads in Essex last month leaving a "dangerous hazard" for road users and pedestrians.
Essex County Council confirmed 25 of the metal covers had been taken in the Basildon district alone in January. Small Manhole Cover
"A missing drain cover is considered as a high-risk problem as it can be a serious danger to the public," said an Essex Highways spokesman.
It was thought a rise in scrap metal prices might be behind the thefts.
Paul Benton, a taxi driver in the Pitsea area, said his wife had seen people dressed as council workers removing the drains.
"We've got cameras and we had a look back and there's a pick-up truck with the orange light flashing on the top," he said.
Mr Benton said he could not see the faces of those involved, but they were wearing high-visibility jackets.
He reported the thefts outside his house after spotting several more in other local roads while driving.
"There could be a nasty accident," he said.
Aaron Russell, who lives in Craylands in Basildon, was on the phone when he spotted a missing cover while walking home.
"I don't know why I looked down, but if I didn't at that point I would have vanished down a massive hole in the road," he said.
"As I've looked around there's manhole covers missing, there's drains, big round drain holes [covers] missing.
"All it takes is for a little toddler to be walking along or riding their bike and that's a major accident.
"I was lucky enough to see it, but for any cars or motorbikes... that's not always something they're going to see...and it could be fatal."
A spokesman for Essex Highways said: "Removing drain covers from their rightful location creates a potentially dangerous hazard for pedestrians and road users alike.
"There are other implications, as missing covers then have to be replaced by Essex Highways, at a cost to the taxpayer."
The council said it had been making the holes safe using cones and plastic sheet grids until replacements could be organised.
In 2013, the government changed the law to try to reduce scrap metal theft.
It meant all scrap dealers and motor salvage operators in England and Wales had to keep records of who they bought from.
Find BBC News: East of England on Facebook, Instagram and Twitter. If you have a story suggestion email email@example.com
Drain brain: The secret life of a gutter enthusiast
Drain cover theft a 'dangerous act of vandalism'
Abandoned ducklings saved from sewer
Scrap metal rule change to cut theft
Drains marked in theft crackdown
Metal thieves target drain covers
'Organised gang' targeting Essex city centre as 'fake homeless' beggars caught
Former Colchester Mayor and councillor quit jobs over wheelchair access in town hall
Here is how you can help five Essex charities win a share of £16,000
Appeal after man assaulted in Loughton
£100k of high-tech GPS gear stolen in raids on 4 farms in Tendring
Rishi Sunak to become next UK prime minister
Russian spy chief blames West for nuclear tension
Xi Jinping's party is just getting started
Hollywood reflects as new Weinstein trial begins
The top US Senate races to watch in 2022 midterms
New ground as tech aims to help boost soil health
India's virtual stars whose real faces you won't see
What these buzzwords say about Xi's China
India celebrates Diwali with dazzling lights
New East African oil pipeline sparks climate row
'When I couldn't fix George, I climbed a mountain' Video 'When I couldn't fix George, I climbed a mountain'
The cost of occupation in Kherson region
The most disgusting films ever made
How job insecurity affects your health
The word Tolkien coined for hope
Vented Manhole Cover © 2022 BBC. The BBC is not responsible for the content of external sites. Read about our approach to external linking.