A murder investigation has been launched after 39 bodies were found inside a lorry container on an industrial estate.
The victims, found at the Waterglade Industrial Park in Grays, included one teenager, Essex Police said.
A 25-year-old man has been arrested on suspicion of murder. He has been named locally as Mo Robinson from Portadown in Co Armagh, Northern Ireland.
Prime Minister Boris Johnson said the perpetrators of the crime "should be hunted down and brought to justice" as police began the task of identifying the victims.
Follow our LIVE updates here...
'Tragedy highlights dangers of people-smuggling'
Richard Burnett, chief executive of the Road Haulage Society, said:
“This tragedy it highlights the danger of migrant gangs people-smuggling on lorries”.
Tory MP James Cleverly tweets:
This is horrific, and so very sad.
This is the entrance to the Port of Holyhead, in North Wales, which is thought to have been used by the lorry carrying a container in which 39 bodies have been found.
Locals say there's some confusion around what's happening
Glen Freeland, from GSF Car Parts which is close to where the bodies were found, said staff could not access the shop on Eastern Avenue on Wednesday morning.
Mr Freeland said:
“The manager went to get into work this morning and it was cordoned off and we’ve been moved to a different area.
“All we know is they found the bodies in the back of a lorry.
“It was a bit of a shock but we’re not 100 per cent sure of what’s happened.”
Local restaurant owner says incident is 'just awful'
A restaurant worker in the industrial estate, who did not want to be named, said the area was cordoned off by police on Wednesday morning.
The Big Blue Food Bus employee said:
“There’s a lot of police and forensics.
“We’ve just seen what has been said online. It’s awful.
“We thought maybe someone had broken into a lorry, but it’s just awful.”
An update from police expected in just over an hour
Essex DCC Pippa Mills will make a statement at Grays Police Station at 1130.
'Shocked': Home Secretary Priti Patel responds:
A witness describes the scene at just after 4am..
Paige Wade was driving past the industrial park at 4.15am on the way home from work.
She told the PA news agency:
"I honestly didn't see much, I had just finished work while driving up Motherwell Way and all you could see was blue flashing lights, as I was driving past there was police tape to cordon off the start of eastern avenue.
"I knew it was serious because of how many police cars and ambulances were there, but the police had parked their cars across the whole access of the road so you couldn't see anything.
"There's always lorries around there as they park up there for the night, I couldn't say whether I did or didn't see the actual lorry in question."
In a statment, Chief Superintendent Andrew Mariner said:
"This is a tragic incident where a large number of people have lost their lives. Our enquiries are ongoing to establish what has happened.
"We are in the process of identifying the victims, however I anticipate that this could be a lengthy process.
"We believe the lorry is from Bulgaria and entered the country at Holyhead on Saturday 19 October and we are working closely with our partners to investigate.
"We have arrested the lorry driver in connection with the incident who remains in police custody as our enquiries continue.
"I appreciate this cordon is going to disrupt the activity of local businesses in the area and we will work to ensure that disruption is kept as short as possible.
"We are working with Thurrock Council to mitigate against any impact our investigation scene will have locally."
Hello, follow our live updates here as this story develops.
