Adrian Gonzales entered a plea of not guilty to 29 counts of child endangerment during an arraignment on Thursday, according to his lawyer, Nico LaHood. The other former officer, Pedro “Pete” Arredondo, waived his right to an arraignment and pleaded not guilty to 10 counts of child endangerment, according to court documents.

The pair face charges for their roles in the bungled police response to the shooting during which officers waited for more than an hour outside a classroom where the gunman was holed up with children, including those who made lengthy calls to 911 emergency services, saying they were in the room with the gunman and surrounded by bodies.

“Mr Gonzales is not guilty of these allegations,” LaHood said after the arraignment. “He showed up that day to try to help those children. And there is evidence that he did help those children that day, he helped evacuate them.”

Arredondo’s lawyer did not return calls seeking comment.

The judge set Sept 16 as the next pre-trial hearing date for Arredondo and Gonzales, who were indicted by a grand jury in Uvalde last month.

Hundreds of law enforcement officers have been criticised for failures in the response to the shooting on May 24, 2022.

Officers left the 18-year-old gunman alone inside the classroom with children while weighing how to confront him. By the time officers stormed in, the school had become the scene of one of the deadliest shootings in US history.

The charges against Arredondo and Gonzales are the first criminal complaints lodged against any responding officers.

Federal and state investigations into the shooting condemned the responding officers’ inaction.

US attorney-general Merrick Garland, in remarks made while presenting the federal report on Uvalde earlier this year, said that “lives would have been saved” had the police immediately confronted the gunman.

In May, the families of the victims filed lawsuits against Meta, Activision Blizzard, and its parent Microsoft, along with gunmaker Daniel Defense, for what they claim was collusion in marketing weapons to young people.