One of the boys who died after falling into a frozen lake while "playing" on the ice was in the water for 31 minutes, an inquest has heard.
Siblings Samuel Butler, six, and Finlay Butler, eight, died along with their cousin Thomas Stewart, 11, and friend Jack Johnson, 10, in Solihull on December 11.
An initial inquest hearing, held on Monday in Birmingham, was told three of the boys were rescued after 22 minutes in the water, while a fourth was pulled from the lake after 31 minutes.
Louise Hunt, a senior coroner for Birmingham and Solihull, described the circumstances as a "devastating tragedy", and said the boys had drowned, as she opened and adjourned the four inquests.
Earlier, she heard evidence from Detective Inspector Jim Edmonds, of West Midlands Police, who gave details of how people initially raised the alarm and the subsequent "heroic efforts" of the emergency services to save the boys.
Mr Edmonds said: "The first three boys were located and brought to the bank at 2.56pm, the same day, and approximately nine minutes later a fourth was rescued from the water.
"Emergency CPR was performed on the children at the scene and they were taken to local hospitals where they received further treatment," he said, adding the boys were at this stage identified.
Mr Edmonds said: "Despite the heroic efforts of everybody involved, all four boys have sadly passed away."
Jack and Thomas died later on December 11, Finlay, the next day, and his brother on December 14, he added.
He added that "all children involved have been accounted for".
"A police investigation is ongoing on behalf of the coroner to establish the facts of the boys' attendance at the lake and also how they fell into the water," said Mr Edmonds.
Inquest to hear pen portraits from families
Setting an inquest to be heard on July 6, next year, Ms Hunt said: "The scope of the inquest will be to look at the circumstances leading to the deaths and the cause of death."
She added the inquest would hear a pen portrait of each young boy from a family member, overviews from each of the three emergency services involved about their responses, together with evidence of the hospital care given.
"I think, in respect, it is fair to say they very sadly died from the effect of drowning."
Having set out the initial cause of death, she added "no post-mortem would be required - to preserve the dignity and respect of each little boy".
She addressed her closing remarks to the boys' families, none of whom were physically present in court, and said: "I'd like to offer you all my sincere condolences.
"Your boys' deaths are a devastating tragedy for you all and it is difficult for us all to comprehend the pain and grief you all must feel at this terrible time.
"In due course, I hope the inquest will help you understand what happened, including the valiant attempts by the emergency services to save the boys."