Three 12-year-old girls are in a serious condition in hospital after they took ecstasy pills.
Police said the teenagers took a type of ecstasy known as "Teddy Tablets" in Salford on Saturday and emergency services were called around 9.50pm.
Greater Manchester Police are now investigating how the children got hold of the potentially lethal drugs.
They warned young people to stay away from the party pills - which have already led to the death of a 22-year-old girl in recent weeks.
Anyone in possession of illegal substances was also urged to hand them in to the police, chemists or medical practitioners.
Last month, a 17-year-old girl died after taking an ecstasy pill known as "MasterCard". Greater Manchester Police made two arrests as part of their investigation into the death
Detective Chief Inspector Chris Walker said: "Sadly, three more young people, who are only 12 years old, have taken ecstasy and ended up in hospital.
"The girls took a type of ecstasy described as 'Teddy Tablets'. It is imperative young people understand the implications and avoid taking drugs, to stop any more young people ending up in hospital.
"We will continue to repeat our warnings in the hope that young people will think twice before taking drugs, after seeing the damage they cause to lives.
"People taking these drugs don't know what they contain or what effect they will have. It's not worth the risk of ending up in hospital or even suffering fatal consequences.
"Police will now be investigating how the girls got hold of these class A drugs and who supplied them.
"Let this be a warning to anyone supplying Class A drugs to young people, and in this case children, you are ruining lives. We will catch you and the full force of the law will be brought down on you."
Anyone with information about where the drugs may have come from is asked to contact police on 101 as soon as possible, or the independent charity Crimestoppers on 0800 555 111.
