Surprise inspections at 31 Dallas public high schools this week revealed that eight were locking exit doors that serve as escape routes during catastrophes, a serious fire code violation.

Fire officials said Wednesday that they issued citations to A. Maceo Smith, Carter, Kimball, Molina, Pinkston, Roosevelt, South Oak Cliff and Skyline high schools.

The citations follow an incident at Samuell High School last week, when students trying to evacuate during a fire ran to an exit door locked with chains because of security problems at the school.

"This is unacceptable. I'm livid," Dallas school Superintendent Michael Hinojosa said Wednesday of the violations. "We've got to follow the fire code."

He said the district has issued a directive to principals to comply with fire codes and advised DISD administrators who supervise principals across the district to "clamp down."

At Samuell, the door chains were eventually unlocked, and there were no injuries from the fire at the school of about 2,000 students. The fire had started in a boys restroom, apparently when a lighted cigarette was thrown into a trash can.

The concern about locked doors came to light when The Dallas Morning News posted a blog item about a teacher's account of students trying to escape the building and encountering the chained door.

Following a Dallas Morning News story Tuesday about the incident, Dallas fire inspectors swept through 31 high schools that day to see if chains were being used on exit doors elsewhere.

"We wanted to make certain that there were not any more locked doors," said fire prevention officer Rebecca Mathews.

She did not provide details about the citations, including whether chains were used to lock the doors.

The number of schools cited – 26 percent of those inspected – concerned and surprised Hinojosa. He said he thought that the Samuell situation was "an isolated incident."

The schools cited include some of the most troubled high schools in Dallas.

Kimball, Pinkston and Roosevelt are considered chronically failing schools under state standards, and they face closure by the state unless they improve this year. Smith and Carter have repeatedly failed federal academic standards.

Skyline is a massive school with more than 4,500 students, potentially making quick exits even more difficult.

Chaining school doors has become fairly common in Texas, as schools weigh security issues against fire safety concerns.

Kurt Harris, an administrator in the State Fire Marshal's office and past president of the Texas Fire Marshal's Association, said the practice has gotten worse as school shootings and other incidents have heightened concerns about school safety.

At Samuell, the door that had been chained was a particular security problem. Though it was locked on the outside, students were opening the door on the inside, in some cases allowing weapons into the school, an assistant principal said.

Dallas fire officials do annual school inspections and respond to complaints about possible code violations, but enforcement can be challenging. Inspections are usually scheduled because of the volume of schools involved. That means school officials know when inspectors are coming and can remove chains on doors.

While he is aware of the security issues, Hinojosa said chaining doors is not the answer.

"We have to find another solution. We've got to come up with something different," he said.

The district also released a statement Wednesday, saying: "Principals are aware that the act of chaining doors is a violation. We are working with principals to resolve any issues with doors that are causing accessibility and safety challenges at school."

Fire officials say that a fine for a violation involving chained doors can vary from hundreds to thousands of dollars, depending on the type of building inspected, the circumstances and the discretion of the judge in the case.

It is not yet known what the schools will be fined for the violations.