Two people are still feared to be missing after four children were pulled from a freezing lake in Babbs Mill Park in Solihull.
The children were rescued from the lake at Kingfisher Country Park in Kingshurst, after members of the public raised the alarm at around 2:40pm on Sunday.
Witnesses reported seeing "six children falling into a frozen lake" just off Fordbridge Road.
Specialist water rescue teams from West Midlands Fire Service continued searching the lake on Sunday evening overnight into Monday morning.
The four rescued children were given immediate life support having suffered cardiac arrests. They remain in a critical condition at Heartlands Hospital and Birmingham Children's Hospital.
The efforts, now referred to as a recovery operation, were continuing overnight. West Midlands Police said they "can't confirm they are looking for anyone else at this stage but will continue to search."
Speaking at a press conference, police urged anyone with information to get in touch. The force asked people not to speculate or share any footage on social media of the incident.
Speaking late on Sunday night, Superintendent Richard Harris said: "We are going to hold the scene tonight and there will be police presence while we ensure, just in case there was anyone else that might have been involved.
"We will keep you advised of any further information as the investigation progresses. We have specialist equipment en route to the scene, with people, so we will continue throughout the course of the night. "I can't confirm we are looking for anyone else at this stage but we will continue to search."
Supt Harris said one officer was suffering from hypothermia as a result of the earlier stages of the search.
He said: "One of our officers suffered some mild hypothermia but I am pleased to say is making a full recovery but yes he went to hospital as a precaution."
Specialist equipment is being shipped to Babbs Mill Park as police, fire, and ambulance services continue the search.
West Midlands Fire Service said in a statement: "At 2:36pm on Sunday 11 December, West Midlands Fire Service, along with West Midlands Ambulance Service and West Midlands Police, were called to Babbs Mill Park in Solihull.
"Reports from the scene and videos on social media indicate that people had been playing on the ice on a pond and had fallen through.
"Our specialist water rescue teams arrived and acted assertively to take control of the scene and carry out rescues using specialist equipment and entering the water.
"Casualties have received medical support at the scene from both firefighters and ambulance personnel prior to being taken to nearby hospitals. The incident is still a search and rescue operation, being led by West Midlands Fire Service.
"We would ask people to allow emergency services at the scene to go about their work in a safe and effective way. We will release further details when appropriate with our fellow blue-light partners."
A West Midlands Ambulance Service spokesman said: "After being rescued, the four children were immediately assessed and actively treated at the scene by ambulance staff. "All four were taken on blue lights to hospital, each with an enhanced care team travelling with the ambulance crew, with treatment ongoing.
"Two were taken to Birmingham Children's Hospital and two to Heartlands Hospital. All four children were said to be in a critical condition on arrival.
"The Hazardous Area Response Team continued to work with colleagues from police and fire at the scene until around 6.30pm to ascertain if there was anyone else in the water. Ambulance resources have now stood down."
St Anthony's RC Primary School, around half a mile from the scene, will be closed today.
A school spokesperson said: "School will be closed for pupils tomorrow due to the incident at Babbs Mill. Please keep all those affected in your prayers at this difficult time."
Worshippers from the New Testament Church of God church in Kingshurst visited to the scene with refreshments for the emergency workers.
Dr Ananya Sandhu said she was continuing to pray for those involved and currently fighting for their lives in hospital. She said she found out about the incident through a neighbourhood watch group which has around 72 families.
Dr Ananya Sandhu said: "When I got back from my church, I was just sitting and I went through and, one after one, the notifications started coming.
"Then they started posting 'guys, something bad has happened at the Fordbridge, we're seeing a lot of ambulances out there'.
"My heart broke, I called up my friends and fellow church members and said 'let's go and offer our prayers'. It was heartbreaking how relentless these people [emergency services] were working to save lives.
"There were a lot of families so we decided to go and come back with drinks.
"It's really sad whatever has happened and I hope and pray that families are strengthened at this given time and we will continue to pray."