KLEIN, Texas – Two students have been charged following the firework explosion inside Klein Forest High School that sent the campus into a panic.

According to authorities, the two students were arrested and charged with arson after the intentionally ignited a firework that was placed inside another container in the cafeteria Tuesday.

“This was a very serious incident that occurred inside one of our schools, and we are fortunate the injuries sustained were minor,” said Harris County Fire Marshal Laurie L. Christensen. “I’m proud of our partnerships with Klein ISD Police, local law enforcement, and the District Attorney’s Office. Our officers were able to quickly identify the suspects, obtain confessions, and file charges.”

According to Klein Independent School District Police Department, this incident happened in the cafeteria during fifth period causing panic among students and teachers.

Four students suffered minor injuries — two hurt by the firework going off and two hurt as they tried to run — officials said. No students or staff members had to be hospitalized following the incident.

After reviewing surveillance footage, police said the student in connection with the crime was identified, detained and later expelled.

The Harris County Fire Marshal’s office said they believe more people may be involved and are using surveillance video captured inside the school to identify them.

The building, which was occupied by nearly 4,000 people at the time of the explosion, was immediately evacuated and students and staff were not allowed back on campus. District officials sent students home and set up a designated area for parents to pick their children up. All Klein Forest High School after-school activities, including home and away activities, were canceled, district officials wrote.

Police remained on the campus overnight, and school buildings remain sealed off as the investigation continues.

Students returned to class Wednesday, but instead of going to their regular first class, they were asked to go to their fifth-period classrooms to collect their belongings.

Mother Michelle Vasquez said she concerned dropping off her daughter at school, ”because there’s kids just doing whatever they want here at the school, they are not being watched."

Klein ISD released a statement about the incident that said, in part:

“The incident is still under investigation, but it is believed that an aerial firework placed in a container was discharged at approximately 1 p.m. Klein ISD Police Officers on duty at the campus immediately responded and began executing the emergency operations plan. Students and staff evacuated the building immediately and all students and staff are safe … As the investigation continues, Klein ISD will hold all involved in this incident responsible to the fullest extent of the student code of conduct and the law. All criminal acts are taken seriously, investigated completely, and addressed through the Student Code of Conduct as well as through law enforcement. The safety of our students and staff is always a top priority in Klein ISD.”

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) said they are assisting the Harris County Fire Marshall’s Office at the scene.

The Fire Marshal’s office also said they were working closely with the Harris County District Attorneys to determine what charges could be filed in this case.

Authorities have not said what charges the expelled student may be facing.