(CNN) -- A 17-year-old student was killed and three other students were injured in stabbings Wednesday morning at a Houston-area high school, Harris County authorities said.
The stabbings happened shortly after 7 a.m. CT during a confrontation at Spring High School, about 20 miles north of downtown Houston, Harris County Sheriff Adrian Garcia said.
Three students were detained for questioning at the sheriff's office, Garcia said. The names of the students involved in the incident weren't immediately released.
One of the injured students was in surgery late Wednesday morning at a hospital, and two others were at a different hospital with minor injuries. Garcia didn't describe the condition of the patient in surgery.
After the stabbings, students were kept in classrooms for safety and so that authorities could interview witnesses, said the superintendent of Spring schools, Ralph Draper. The school intends to dismiss students for the day at noon, he said.
"We do believe the persons of interest (in custody) ... are the only persons of interest that we need to have in custody," Garcia said.
The sheriff said that "there has been some information that this may have been gang-related," but he stressed that no conclusions had been made because the investigation was in the early stages.
Information on what led to the stabbings was limited. Garcia said an encounter between students turned into a physical confrontation involving "cutting instruments of some sort."
Investigators haven't found any weapons, the sheriff said.