Photos have emerged of the scene where 39 people were found dead in a lorry container.

Essex Police said it was called by the ambulance service shortly before 1.40am on Wednesday following the discovery of a lorry container with people inside at Waterglade Industrial Park, Eastern Avenue, Grays.

Some 39 people were pronounced dead at the scene. Early indications suggest 38 are adults and one aged in their teens, police said.

A 25-year-old-man from Northern Ireland has been arrested on suspicion of murder.

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."

At a press conference at Grays police station, deputy chief constable Pippa Mills said police were unable to identify the bodies.

She said: "Please appreciate we are in the early stages of what is likely to be a lengthy investigation."

She added: "I'm unable to say at this stage how long the cordon will be in place.

"But please let me reassure you that my officers and partners will be doing everything they can to release the scene as soon as possible."

She said: "This is an absolute tragedy and very sad day for Essex police and the community.

"We will continue to work alongside many other partner agencies to find out what led to these deaths.

"I would like to appeal to anyone who has any information to contact my officers at the major investigations team."

Mr Burnett told PA the container appeared to be a refrigerated unit and described conditions for anyone inside as "absolutely horrendous".

Temperatures in such units can be as low as -25C if frozen products are being transported, causing humans to "lose their lives pretty quickly", he said.

He went on: "It's going to be dark. If the fridge is running it's going to be incredibly cold.

"The only place to go to the toilet is on board the back of the trailer. You can imagine if they've been in there for days then there will be faeces, there will be urine."

The National Crime Agency (NCA) said: "We are aware of this tragic incident which is now the subject of a murder investigation being led by Essex Police and we have deployed NCA officers to assist.

"We are working with partners including Essex Police and Immigration Enforcement to provide specialist support to urgently identify and take action against any organised crime groups who might have played a role in causing these deaths."