Police made 'wrong decision' at Texas school shooting - safety official
"If I thought it would help, I would apologise," Steven McCraw said during a heated press conference on Friday.
Officers delayed entering because they did not believe it was still an "active shooter" situation, he said.
But pupils inside made multiple calls begging for police to come.
Mr McCraw confirmed there had been a 40-minute gap from the police unit's arrival at Robb Elementary School to the moment they decided to storm the classroom where the gunman had barricaded himself.
The senior officer on the scene decided to wait until the school janitor arrived with the keys because they thought that either "no kids were at risk" by then, or "no-one was living anymore".
The delayed response, combined with video footage showing frustrated parents being tackled and handcuffed by police while the gunman was still inside the school, has led to growing public anger and scrutiny of how law enforcement handled the situation.
Authorities have also struggled to give a clear timeline of how events unfolded in Uvalde.
On Friday, Texas Governor Greg Abbott said he was "livid" that he had been "misled" about certain information, which he had made public in a news conference earlier this week.
"As everybody has learned, the information that I was given turned out in part to be inaccurate," he said.
-- Courtesy of BBC News