Police didn't immediately confront the gunman as Texas school shooting unfolded because they 'could've been shot,' lieutenant says

• Law enforcement is getting slammed for its response to the Uvalde school shooting as it unfolded.
• Police waited for Border Patrol before confronting the gunman, officials said.

Law-enforcement officers did not immediately confront the gunman as the shooting at Robb Elementary School unfolded because they "could've been shot," a Texas Department of Public Safety official told CNN on Thursday.

Local and state authorities responding to the deadly shooting in Uvalde, Texas, on Tuesday had waited for a US Border Patrol tactical team to arrive to take out the gunman, officials previously said.

It remains unclear how long they waited, though officials said Wednesday that roughly 40 minutes to an hour had passed between the time the shooter entered the school and was shot and killed by a Border Patrol agent.

Texas DPS Lieutenant Chris Olivarez told CNN on Thursday: "The active shooter situation, you want to stop the killing, you want to preserve life, but also one thing that — of course, the American people need to understand that officers are making entry into this building. They do not know where the gunman is."

"At that point, if they pursued it any further — not knowing where the suspect was at — they could've been shot, they could've been killed and, at that point, that gunman would have the opportunity to kill other people inside that school."

Officials have been trying to piece together an exact timeline of how the shooting, which left 19 children and two adult, unfolded, and how law enforcement reacted.

They have faced mounting criticism for the slow response time, with policing experts saying that a greater sense of urgency from them could have saved lives.

Bystanders and parents who were outside the school when the shooting unfolded said they were so frustrated with police that they considered storming the building themselves.

One mother ended up jumping the school fence and running inside the building herself to grab her two children, The Wall Street Journal reported. The woman told The Journal she did so because officers were "doing nothing."

"They were just standing outside the fence," she told The Wall Street Journal. "They weren't going in there or running anywhere."