Three people were wounded, one critically, when gunfire erupted during an altercation between two people at a Houston community college, the latest in a series of shootings on US college and school campuses.
Two people "of interest" in the Lone Star College shooting were detained for questioning, including one with a student identification, according to authorities.
"We are questioning them now," Harris County Sheriff's Office Captain WK Melacon told a press conference at the scene.
Authorities said the two people involved in the argument were in hospital.
A maintenance worker who had been standing nearby was shot in the leg, and a woman with a student ID was taken to a hospital with a medical issue that was not a gunshot wound, they said.
An ambulance dispatcher said his company had transported three people to local hospitals. One of them was in critical condition and the other two were in "urgent" condition, he said.
The campus was searched and the all clear given, sheriff's officers said. Classes were expected to resume on Wednesday.
The shooting at the community college with some 10,000 students was the latest incident at a US school since a gunman massacred 20 children and six adults in Connecticut in December.
Acting Harris County Sheriff Armando Tello said the first call to police about the dispute at the college was made at 12.51pm local time and sheriff's deputies arrived two minutes later.
The argument began as a verbal exchange and escalated to shooting, authorities said. A handgun was involved but no other information was given about the weapon.
The shooting at the North Harris campus of the community college system occurred outside in the centre courtyard, School Chancellor Richard Carpenter said.
Four schools in the Aldine district near Lone Star College were also locked down, said Leticia Fehling, a spokeswoman for the district.
Student Amanda Vasquez said she was waiting for an English class to start in a campus building when she heard shots.
"I heard about six shots ... Kids started rushing down the hallway. It really happened so fast," she told CNN news.
Vasquez said people in the classroom closed the door, turned off the lights and put a table against the door.
The Connecticut massacre shocked the nation and led President Barack Obama to push for stricter gun control. Texas has a concealed carry law that allows residents with permits to carry handguns, but they are not supposed to be taken into school buildings.
The Lone Star College System is the largest institution of higher education in the Houston area, according to its website. Student enrolment is 90,000 and there are six colleges in the system.
There have been three separate shootings at schools and colleges in the United States in the past two weeks.
On January 10, a student armed with a shotgun opened fire at a California high school, wounding a fellow student. A second student also received minor injures at Taft Union High School in Taft, California.
On January 15, a student armed with a pistol opened fire at Stevens Institute of Business and Arts in downtown St Louis, shooting a school employee and then turning the gun on himself.
Also on January 15, two people were killed and a third wounded when gunfire broke out in the parking lot of a community college in eastern Kentucky. Authorities said that shooting was a result of a domestic conflict.