Investigations are continuing at a Tyneside primary school where staff and pupils suffered suspected carbon monoxide poisoning.
Gas boilers at a primary school are being examined after children fell ill from carbon monoxide poisoning.
Emergency services were called to Crookhill Primary School in Ryton, near Gateshead, on Tuesday after pupils complained of feeling sick and dizzy.
Emergency crews took 25 pupils and a teacher from Crookhill Primary School in Ryton, near Gateshead, to hospital after they complained of feeling sick.
Ambulances and minibuses took a teacher and 25 pupils to hospital.
The Health and Safety Executive (HSE) said they suspected three gas boilers under a classroom were responsible.
The school remained closed on Wednesday as a Health and Safety Executive investigation began.
The school remained closed on Wednesday as the HSE and specialist engineers examined the boilers.
The children were treated at South Tyneside District Hospital, Newcastle General and the Queen Elizabeth in Gateshead. Only one girl was detained overnight for observation.
The children were treated at South Tyneside District Hospital, Newcastle General and the Queen Elizabeth in Gateshead on Tuesday.
The levels of carbon monoxide measured are not thought to be worrying Consultant Bob Jarman
Eight were found to have raised levels of carbon monoxide and were treated with oxygen.
Bob Jarman, A & E consultant at Gateshead Health NHS Foundation Trust, said: "All have now been tested for carbon monoxide poisoning.
HSE control
"Eight children and their teacher were found to have raised levels of carbon monoxide and were treated with oxygen.
Bob Jarman, A & E consultant at Gateshead Health NHS Foundation Trust, said the levels of carbon monoxide measured were "not thought to be worrying."
"However the levels of carbon monoxide measured are not thought to be worrying and their condition is being monitored."
Only one girl was detained overnight for observation.
Crookhill Primary School head teacher Louise Easton said the main concern was to ensure the health and safety of all pupils and staff.
Pam Waldron, head of HSE operations in the North East said: "The focus of our enquiries is the three gas fired boilers underneath the classroom and their fluing arrangements.
'Distressed state'
"Yesterday we issued a notice that the boilers should not be used and access to the boiler room is currently under HSE control."
They had been taken to hospital as a precaution, and parents of all children were being kept informed of the situation.
Representatives from the school and Gateshead Council will meet on Wednesday to discuss the progress of the investigation.
Malcolm Downs, a parent of a child at the school, said: "There were some children in a distressed state, but we were more upset that we did not know what was going on.
"My daughter got a bit upset when she heard one of her friends had been involved."
Mr Downs runs a shop opposite the school and said he became aware of the incident when he returned to the premises and spotted an ambulance and fire engine.
He said: "There was no smoke or flames so I thought the fire engine and ambulance had just visited the school for the children to look at."
