Nearly 20 officers stood in a hallway outside of the classrooms during this week’s attack on a Texas elementary school for more than 45 minutes before agents used a master key to open a door and confront a gunman, authorities said Friday.

The on-site commander believed the gunman, 18-year-old Salvador Ramos, was barricaded in a classroom at Robb Elementary School in Uvalde during Tuesday’s attack and that the children were not at risk, Texas Department of Public Safety Director Steven McCraw said at a news conference.

“He was convinced at the time that there was no more threat to the children and that the subject was barricaded and that they had time to organize” to get into the classroom, McCraw said.

“Of course it was not the right decision. It was the wrong decision,” he said.