An elementary school classroom in Southern California was reportedly evacuated after a parent assaulted a staff member and then barricaded a classroom, holding a teacher captive, district officials said Tuesday.

The suspect barricaded the doorways of a classroom with a teacher inside a room of the  Castleview Elementary School in Riverside shortly after 11 a.m. said Justin Grayson, a spokesman for the Riverside Unified School District. The situation was ongoing at that point, ABC-affiliate KABC reported. 

Smoke was said to have been briefly coming from the classroom, police said. 

According to reports, the incident may have occurred when a parent attempted to remove their child from the school and was denied. Authorities said that it was a developing story and that police were still attempting to determine a motive.

Students were not present in the classroom during the incident, and students in the school were moved to a nearby park, Grayson said.

A Riverside police spokesperson indicated that the individual who detained the hostage was thought to be an adult and not a child, and all students were moved to safety.

The district delivered a statement to all the families of students, Grayson said, and officials were making sure all 670 children were accounted for at the school.

Early Tuesday, the school district said in a statement that the elementary school had been placed on lockdown because of "a disturbance inside of a classroom," and that the Riverside police were investigating.

"At this time Castle View Elementary has been placed on lockdown due to a disturbance inside of a classroom," the statement read. "Riverside Police Department is on site and actively working to resolve the situation. All students are being evacuated to a safe location off-campus. Unfortunately, at this time we cannot release any students until the lockdown order has been lifted by RPD. We will communicate with you again as soon as the situation is resolved and give you further instructions on student pickup."

Many took to social media to comment on the incident.

"Those poor kids," one Facebook user wrote. "This is a hard year for kids with everything that they have had to endure both in the news and in our community! Can 2017 be over already?”

Praying for the safety of all," another wrote. "Is there any other measures for other schools as well or only castlview elementary?"

This is a developing story. Please check back for more details. 

Classroom A school in California was evacuated after a parent apparently assaulted a staff member and trapped a teacher in a classroom. Students are pictured on June 16, 2006 in Miami, Florida. Photo: Getty Images