AUSTIN (Nexstar/Texas Tribune) — Former police chiefs, federal law enforcement officials and experts are criticizing the Uvalde CISD police chief’s explanation of why the response to the Robb Elementary School shooting took so long.

In an exclusive interview with KXAN’s news partners at The Texas Tribune, Pete Arredondo defended his actions and said he hadn’t spoken out sooner because he didn’t want to compound his hometown’s grief or point blame.

“The only thing that was important to me at this time was to save as many teachers and children as possible,” Arredondo said.

The chief of police for the Uvalde school district spent more than an hour in the hallway of Robb Elementary School. He called for tactical gear, a sniper and keys to get inside, holding back from the doors for 40 minutes to avoid provoking sprays of gunfire. When keys arrived, he tried dozens of them, but one by one they failed to work.

“Each time I tried a key, I was just praying,” Arredondo said. Finally, 77 minutes after the massacre began, officers were able to unlock the door and fatally shoot the gunman.

Arredondo confirmed to the Texas Tribune that he did not go into the building with his radio, saying that made him unaware of the 911 calls coming from children and teachers inside the classrooms, begging for help. Texas Department of Public Safety officials and news outlets have reported that the shooter fired his gun at least two more times as police waited in the hallway outside the classrooms for more than an hour.

Former Austin and Houston police chief Art Acevedo said a more coordinated response amongst the various law enforcement agencies on the scene could have saved lives.

“We failed, and there’s no way getting around that,” Acevedo told Nexstar. “The most important piece of that command control is having communication with your team. Not having master keys for a school — that is your jurisdiction, that school — and accessing classrooms is really important.”

Acevedo and other former law enforcement officials said it is standard protocol to always go into an active threat situation with a radio.

“I think it really calls into question the suitability to be the chief in that place or any other place,” he said.

A retired police chief from Rockford, Illinois, agreed that radio communication is essential for making calls for help, coordinating a response, or communicating if medical attention is urgently needed.

“You want to have a radio — or have someone with you that has a radio — so you want to be able to coordinate other resources, your fellow officers, other police personnel that are responding to the scene,” said Chet Epperson, former Rockford Police Chief.

Epperson was more understanding of the likely circumstances Arredondo was facing, but still agreed going in without a radio was a mistake.

“I can’t imagine what he was thinking in terms of the pressure, the amount of things and obstacles that were taking place,” Epperson said.

He said it’s difficult to analyze the situation and what he might have done without all of the information, as multiple investigations into what happened are ongoing. However, Epperson said there needed to be a backup plan when Arredondo was unable to breach the classroom door where the gunman was inside. Arredondo said that was because it was built sturdily with a steel jamb–impossible to kick in.

“There’s got to be Plan B…how can we work around that? How can we get through that steel door? Because you don’t want to wait,” he said. “Waiting just causes the shooter–the shooters just end up shooting the gun at more people and killing and injuring people.”

George E. Hyde, Arredondo’s lawyer, said those criticisms don’t reflect the realities police face when they’re under fire and trying to save lives. Uvalde is a small working-class city of about 15,000 west of San Antonio. Its small band of school police officers doesn’t have the staffing, equipment, training, or experience with mass violence that larger cities might.

One former Houston police officer and DEA agent agreed to speak to Nexstar on background, saying he did not want to comment before the investigation is complete. He said one thing is certain: in a high-threat situation, it’s critical to make fast, calculated decisions when presented with obstacles because every minute that goes by presents more risk to whoever is in a shooter’s path.

The Texas Tribune contributed to this report.