Police are continuing to question an excluded student over two stabbings at a school that left one teenager in a critical condition.
The two victims, both 15, were taken to hospital following the attack at the Kingsdale Foundation School in Dulwich, south London.
The Metropolitan Police said one teenager remained in a critical condition and another had been arrested.
The school will open today and concerned parents would be kept updated, according to its headteacher.
Steve Morrison said: "The police have informed us there is no reason it shouldn't be open.
"At this stage I understand they are satisfied they have the suspect they wish to talk to.
"We've been informed that a 16-year-old is assisting the police with their inquiries.
"We are fully collaborating with the police and are not at liberty to comment further or speculate over the source of any misinformation released into the public domain."
Mr Morrison said a student who was excluded from the school site was involved.
Both victims were taken to a south London hospital but the teenager with the less severe injuries has since been released.
Some students were held inside while emergency services responded to the situation, which took place shortly before 3.30pm on Thursday.
Police spent a number of hours speaking with staff inside, while teachers who left the premises declined to comment.
A Southwark Council spokeswoman said: "We are assisting with the police investigation in any way that we can."