In the latest statement, Lincolnshire Police said: "We remain on scene with the Fire and Rescue Service and other specialists from the Forensic Science Service, continuing a methodical and meticulous investigation of the scene today and we expect this to take some time.
"We hope to establish how the fire has started and the cause of the blaze. It is painstaking work and there will be forensic tests ongoing, all which take time for any conclusion to be drawn.
"We are treating the tragic death of the two year old girl as unexplained at this time."
The police said specialist officers are supporting the family following this tragic incident.
The were on holiday at Sealands caravan park in Ingoldmells when the fire broke out. Family members who escaped the fire were the two-year-old’s siblings, all aged under 11 and their mum who is in her 30s.
Detective Inspector Jo Fortune, Senior Investigating Officer, Lincolnshire Police, said: “Our thoughts are very much with the family and friends of those involved in this tragic incident and I send our condolences. We will do everything we can to establish what has happened.
“I would like to pass on my personal thanks to everyone who helped on the evening and has supported the family too. It was a very serious and frightening time. “
The residents who were asked to leave their caravans have now been able to return.