A law enforcement source told NBC News that three people were shot and one person possibly suffered a heart attack at the North Harris campus of Lone Star College. A college spokesperson said that two of the people shot were students and that a gunman was also shot.
NBC station KPRC-TV reported that police had one person in custody and that second person was also detained after a search in a local sub-division.
Federal authorities said it's not clear whether the first person detained in the shooting was a student.
It appears the shooting was the result of animosity between two people, federal authorities said, and that students got shot in the cross-fire. Several federal officials have said it was gang-related, but the exact nature of the relationship remained unclear.