Gunfire erupted inside an Iowa high school on what should have been the first day of students’ spring semester, police said, though the extent of the violence remains unclear.

The first reports of a possible active shooter at Perry High School started flooding in on Thursday around 7:40 a.m. local time, according to authorities.

Law enforcement officers spanning multiple agencies — including the Dallas County Sheriff’s Office and the Perry Police Department — raced to the high school in the suburbs some 25 miles northwest of Des Moines. When they arrived on the scene, within minutes of the initial call, officers discovered multiple people suffering gunshot wounds.

Authorities declined to provide further details regarding the victims, including the number of people shot and their conditions.

“There are a bunch of speculative numbers floating around,” said Dirk Cavanaugh, Perry’s mayor. “We have no confirmed numbers of who was involved yet.”

Multiple law enforcement officials briefed on the matter told NBC News the shooter died from a self-inflicted gunshot wound. Police did not provide any information about the suspect, citing ongoing law enforcement efforts.

Video shared on social media shows police officers and law enforcement cruisers circling the building, among them Iowa State troopers, who blocked off the streets surrounding the school, according to WHO13.

FBI’s resident agents at its Des Moines office also responded to assist the Iowa Division of Criminal Investigation, the FBI said. The Bureau of Alcohol, Tobacco, Firearms and Explosives is similarly on the scene.

During a brief news conference, Dallas County Sheriff Adam Infante said school had not yet begun for the day, and few people were in the building when the gunfire started. Some students reported being turned away as they arrived for their first day of classes in the new year.

Zander Shelley, 15, was in a hallway when he heard gunshots and then dashed into a clos-by classroom. His father, Kevin Shelley, said his son was grazed twice and then texted him from his hiding spot. Rachael Kares, an 18-year-old senior, was just finishing a rehearsal for jazz band when she and her friends heard what sounded like four gunshots.

We all just jumped,” Kares said. “My band teacher looked at us and yelled, ‘Run!’ So we ran.”

Infante emphasized that “there is no further danger to the public” and that the “community is safe.”

Perry High School serves nearly 600 high schoolers as part of the Perry Community School District, which is home to some 1,800 students, according to its website.

By 8:25 a.m., the nearby middle school was cleared. A second team declared the high school safe just minutes later, according to WHO 13. The elementary school was also evacuated as a result of the violence, and students were dismissed for the day shortly after 8:30 a.m.

“We’re just now working backwards trying to figure out everything that happened,” Infante said of the ongoing investigation.