News of the discovery of 39 dead bodies in a lorry in Thurrock, Essex, this morning has dominated Prime Minister's Questions.
It is believed that of the bodies found in the container - which came from Bulgaria - 38 are adults and one is a teenager.
Opening the Commons debate, Boris Johnson called it an "unimaginable tragedy".
He said he was receiving regular updates on the situation, and that the Home Office will work closely with Essex Police.
The Prime Minister added that he had a "strong desire" to find out who was behind the incident.
The lorry was found at Waterglade Industrial Park in Grays, Essex
"The perpetrators of that crime, and indeed all those who engage in similar activities - because we know that this trade is going on - all such traders in human beings should be hunted down and brought to justice," he said.
"It is hard to put ourselves in the shoes of those emergency services as they were asked to open that container and to expose the appalling crime that had taken place."
And MP for Thurrock Jackie Doyle-Price, said the incident had shown a "contempt for human life".
"To put 39 people into a locked, metal container shows a contempt for human life that is evil. The best thing we can do in memory of those victims is to find the perpetrators and bring them to justice," she said.
Jeremy Corbyn asked MPs to reflect on the 'unbelievable human tragedy'
Tributes to the 39 victims also came from opposition leader Jeremy Corbyn, who asked for silence to reflect on the "unbelievable human tragedy".
And the SNP's Westminster leader Ian Blackford said the event "should distress us all".
The driver of the lorry, a 25-year-old from Northern Ireland, has been arrested on suspicion of murder.
Police have asked anyone with information to contact them on 101 or via the Essex Police website.