Siblings Samuel Butler, six, and eight-year-old Finlay Butler died along with their cousin Thomas Stewart, 11, and Jack Johnson, ten, on December 11,
They were rescued from Babbs Mill Lake, in Kingshurst, Solihull, near Birmingham, and rushed to hospital.
The deaths of Finlay, Thomas and Jack were confirmed on Monday while Samuel died in hospital on Wednesday.
At a vigil over the weekend, hundreds more people brought candles, bouquets, children’s toys and balloons to the spot, as people struggle to deal with the scale of the loss.
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.
Senior Coroner for Birmingham and Solihull Louise Hunt described the circumstances as a “devastating tragedy”, as she opened and adjourned the four inquests.
Earlier, she heard Jack, from Kingshurst, and Thomas, of Shard End, Birmingham, were identified by their parents at Birmingham Heartlands Hospital, and the two brothers; Finlay and Samuel, also both from Kingshurst, at Birmingham Children’s Hospital.
She also 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: “West Midlands Police first contact at 2:34pm on Sunday, December 11, reporting four children playing on a frozen lake at Babbs Mill Park had fallen through the ice, into the water.
“Further calls were received from other members of the public, also reporting children had fallen in to the water, but with some variance as to the number of children involved
“Emergency services responded at pace and at arrival it became quite apparent this was a major incident and there were numerous members of the public at the location, reporting children had tragically fallen under the water.”
He said the police as well as West Midlands Fire Service and West Midlands Ambulance Service attended.
Turning to the rescues, 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 said “all children involved had been accounted for”.
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 called for the families’ privacy to be respected so they might process their loss, and be able to grieve.