Authorities said there is a possibility some of the 10 victims in the Santa Fe High School shooting could have been hit in the crossfire during a 25-minute gun battle between 17-year-old Dimitrios Pagourtzis and school resource officers who were joined by responding sheriff's deputies.

Galveston County Sheriff Henry Trochesset said authorities were waiting for medical examiner autopsy reports to make a determination if that occurred, CNN reported.

Galveston County District Attorney Jack Roady said autopsy reports won't be released while the case is pending, The Associated Press reported.

Pagourtzis, who was captured, wasn't hit in the attack even though officials have described him engaging in a drawn-out firefight with police.

School resource officers reportedly arrived outside the high school's art lab section four minutes into the shooting, CNN noted, but reports indicated the shooting lasted as long as 30 minutes.

Galveston County Judge Mark Henry, the county's top administrator, said police exchanged rounds with Pagourtzis "for quite a while" before he surrendered a half-hour after the first reports of a shooter on campus, the AP said.

"They said there was a lot of firepower and a lot of rounds exchanged," Henry said.

A "decent amount of cameras in the school" will help investigators piece together a timeline, Trochesset told CNN. A probable cause affidavit had said the suspect had told an investigator he acted alone and spared people he liked because he wanted his story told.

According to the AP, early witness accounts and recordings from emergency dispatch describe a 30-minute nightmare, but the AP said authorities continued to keep details close.

Among the biggest unknowns is when the confrontation between police and Pagourtzis began after he had opened fire on the art lab with a shotgun and .38 caliber handgun shortly after the first bell on Friday morning.

Roady declined to answer questions about the shootout and investigation, including whether police may have hit any students in a gunfight with the shooter.

Officials have not yet released 911 tapes, but on emergency dispatch recordings from Galveston County, captured by Broadcastify.com, a female voice is heard saying "more shots fired" about 10 minutes after authorities first received reports of gunfire. Five minutes later, a male voice says the suspect is "possibly going to be barricaded" with additional reports of shooting a few minutes after that.

"He's actively shooting. He's in the art room. We've got, we've got shots fired right now. We need you all up here," a male voice says at what appears to be about 15 minutes after the shooting began.

Henry said investigators were still working on the timeline.

One Santa Fe school police officer who responded to the attack was shot and remained in critical condition, according to the University of Texas Medical Branch.

Zach Wofford, an 18-year-old senior, was across the hallway when the shooting began and said he heard gunfire that lasted 10 to 15 minutes from the art classroom. That's where Breanna Quintanilla, a 17-year-old junior, was when the attack began. She said Pagourtzis had aimed at her and missed but that it ricocheted into her right leg.

She recalled the voice she heard after the first sound of gunfire in the class: "If you all move, I'm going to shoot you all."