The teacher who was stabbed at the school is “recovering well” after being released from the hospital.
The Tewkesbury Academy executive committee said the teacher, who was attacked shortly after 09:00 BST on Monday, did not intervene in the student’s fight.
Gloucestershire schools have reopened earlier after “careful consultation with police”, a spokesman said.
A teenager is being questioned after being arrested on suspicion of murder.
A spokesman for Tewkesbury Academy said: “After a careful assessment and consultation with the police, Tewkesbury Academy has reopened today.
“We feel it is important that our students can return to a sense of normalcy in their schools, where we will provide an additional range of emotional and mental support to students and staff. pellets.
“Police will maintain a presence at the school in the coming days to make sure.”
Gloucestershire Police said they were keeping an “open mind” about the possible motive for the attack.
Two other local schools were ordered to close as police hunted down the suspect on the Tewkesbury Academy campus following the stabbing.
A teenager was arrested two hours later in the village of Stoke Orchard, about four miles away, after a chase that involved armed officers, plainclothes officers and the National Aviation Police.
The school’s statement also thanked the police for their “priceless help and reassurance” as the incident unfolded.
“And finally, a big thank you to all of our Tewkesbury colleagues for their composure and professionalism during an extremely difficult day, as well as our students and their families for their patience. , their resilience and support,” it added.
A spokesperson for Gloucestershire County Council praised the “staff and students” at the school for how they responded to the incident.
“Our thoughts and prayers go out to the staff member injured in the attack and his family, as well as to the students, the wider school community, and the parents who have had to face the agony of waiting for news of their children’s safety.
“While thankfully this type of incident is extremely rare, the impact on those involved can be huge, so we are doing all we can to support schools as they support learning.” students, staff and the wider school community,” they said.