The head of the Texas Department of Public Safety said Friday law enforcement officers should have entered the classroom sooner in Uvalde, Texas, during a massacre that left 19 children and two teachers dead earlier this week.

The commander at the scene of the shooting at Robb Elementary School decided the incident had transitioned into a “barricaded suspect” situation, not an “active shooter” — a decision that Steven McCraw, director of the Texas Department of Public Safety, said was wrong while speaking during a news conference.

“From the benefit of hindsight, where I’m sitting now, of course it was not the right decision. It was the wrong decision. Period. There’s no excuse for that,” McCraw said.

The gunman entered the school at 11:33 a.m. Tuesday, but officers did not enter the classroom where the shooter was holed up and kill him until 12:50, McCraw said. During that time, multiple 911 calls from inside the classroom said there were students alive and asking for police to enter the classroom to come help them, McCraw said.

Police officers had entered the school and were in a hallway within minutes of the gunman entering the school, and two officers received grazing wounds from the suspect in an initial encounter with him, McCraw said. But officers remained in the hallway for around an hour, McCraw said. Most of the shooting from the gunman, which included hundreds of rounds fired, occurred within minutes of him entering the school, McCraw said.

TEXAS SCHOOL SHOOTING VICTIMS LIST: Families mourn those lost in the Texas school shooting

Rep. Castro asks for FBI investigation

A U.S. congressman is calling for the FBI to investigate law enforcement’s response to the massacre in Uvalde, Texas, that killed 19 children and two teachers earlier this week.

Rep. Joaquin Castro, D-Texas, wrote a letter to FBI Director Christopher Wray citing conflicting reports given by police about the timeline of events of the shooting and officers’ interactions with the shooter. 

Texas state police have launched an examination of law enforcement’s response to the shooting. Witnesses and neighbors have contested officials’ statements about the events, while law enforcement officials have revised parts of their accounts. Officials have sought to assure the public that they responded immediately to the shooting as complaints surfaced about a delay in taking action and entering the school.

Castro said answers were needed about conflicting accounts: “Whether the school security officer and the gunman exchanged fire outside the school,” and, “How long law enforcement officers were in adjoining classrooms while the gunman barricaded himself in a classroom with students and teachers.”