Sterling High School
Among them was a stabbing at about 10 a.m. at Houston ISD's Sterling High School, which was briefly placed on lockdown following the event.
HISD said the stabbing stemmed from a fight between two students on campus.
The student stabbed was taken to the hospital in unknown condition. The suspect, also a student at the school, was placed into custody.
READ MORE: Lockdown lifted at Sterling HS after student stabbed during fight, suspect arrested, HISD says
Elsik High School
Then, Alief ISD said Elsik High School was placed on lockdown because a student reportedly brought a kitchen knife to school.
"Once all involved parties were apprehended, the campus was placed in secure status," the district said in a statement.
The secure mode was later lifted, and classes resumed as normal. The district did not release any other details about the incident.
Spring High School
Shortly after that, Spring ISD announced a student at Spring High School was detained for having a firearm on campus.
In a letter to parents, the principal said the weapon had been located in a theater and safely retrieved.
Spring ISD's police department is investigating how the gun made it on campus.
District officials added that the student could face criminal charges.
Bellaire High School
At about 12:15 p.m., HISD said Bellaire High School students remained in their classrooms after the campus received a bomb threat.
Police responded to the school while the threat was being investigated, officials said.
"After a thorough interior and exterior building search, HISD PD determined there was no threat to our campus. As of 2:20 p.m., our campus has been cleared by HISD police. Classes continue as normal," an email from the school principal read.