Detectives made a shocking discovery as they found 39 bodies, including that of a teen inside a truck at an industrial park in Essex, U.K.

They were called to the Waterglade Industrial park, where they found the bodies in the back of a truck container in the wee hours on Wednesday morning. Emergency services were called at the location who then pronounced the victims dead.

"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," Chief Superintendent Andrew Mariner said in a statement. 

The U.K. police have launched a murder investigation into the incident, which is believed to be one of the largest murder probes carried out in the U.K. ever.

The 25-year-old driver of the truck who is from Northern Ireland has been arrested by the police on suspicion of murder, the Essex police said. The victims found in the truck are still being identified.

"We have arrested the lorry driver in connection with the incident who remains in police custody as our enquiries continue," Mariner added.

According to the police the lorry, which was originally from Bulgaria, entered the U.K. through Holyhead, a port in Wales, on Saturday, Oct. 19. 

The horrific crime has sent shockwaves across the country, with U.K Prime Minister Boris Johnson among the people who were appalled by it.

The police have cordoned off the area for further investigation and access to and from the industrial park has been closed.

“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,” the police said in their statement.

Jackie Doyle-Price, the Conservative MP for Thurrock, said that he was sickened to hear about the 39 bodies being discovered. 

Aerial images of the scene show black screens set up behind the white truck with forensic tents nearby.

The nationality or the destination where the victims were headed to remains unknown as of now.