Police are investigating whether 19 people who drowned picking cockles in Morecambe Bay were working for a criminal gang.
Policemen pass piles of cockles as they search Morecambe Bay
The group of more than 30 cocklers were caught in rising tides on Thursday night. A total of 16 people survived.
Fourteen survivors were Chinese nationals, including nine asylum seekers and five illegal immigrants.
The deaths, which police say are suspicious, have sparked calls for more protection of migrant workers.
While the search was suspended as darkness fell on Friday night, Lancashire police will continue gathering evidence for a criminal investigation.
Assistant chief constable Julia Hodson, of Lancashire Police, told a news conference on Friday: "Nobody deserves to die in these circumstances."
She added: "We still do not know if the people involved are illegal workers, we still do not know if they had the required permits and if they were working for anyone else."
She said five of the survivors, who are all in the care of social services, were unknown to immigration service and four have since claimed political asylum.
The two non-Chinese people were white European.
Cantonese and Mandarin translators are helping police to question survivors but no formal statements are being taken until they have recovered.
Morecambe Bay is a popular spot for cocklers
Police are also trying to identify the bodies and contact next of kin.
The Health and Safety Executive, the Chinese Embassy, the Coroner's Office and Lancashire County Council are also helping police.
A red pick-up truck containing bags of cockles was removed by police on Friday night, having been pulled from the sand at low tide.
Earlier on Friday, Ms Hodson said officers were considering the possibility of criminal charges.
She described gang bosses who profited from the slave labour of illegal immigrants as "criminals of the worst
Chief constable Paul Stephenson told BBC Radio 4's World at One programme the problem of illegal immigrants engaged in cockling was one officers had been dealing with for some time.
"We would not be surprised to find illegal immigrants as part of this tragedy last night," he said.
The group of more than 30 cocklers were trapped by rising water in the Hest Bank area of the Lancashire bay.
They were pulled out of the near freezing sea during a huge rescue effort by coastguards, lifeboats and the RAF overnight.
Police say 17 of the dead are men while two are women. The 19th victim was recovered later on Friday afternoon.
The Bishop of Lancashire, who heads the Catholic Church's migration policy, called on the government to ensure all contractors were licensed.
He said: "This appalling tragedy raises fundamental questions about whether or not we are providing enough protection to these migrant workers who contribute enormously to our economy and our welfare."
The bishop said it was "crucial" that all MPs signed up to last month's Early Day Motion which called for the registration and licensing of all labour providers, also known as gangmasters.
"The government ought to recognise that gangmaster voluntary codes are proving inadequate," he said.
The area is known to be treacherous
TUC General Secretary Brendan Barber said the "full force of the law" should be brought against whoever were the victims' bosses.
"This incident provides a rare glimpse into the dangerous and
exploitative conditions faced by many migrant workers on a daily basis," he said.
The police in Lancashire are appealing for help in identifying the victims.
Police issued two numbers in connection with the incident:
For witnesses or those with information - 01524 63333
For worried relatives - 0870 9020999