Nearly 48 hours after one of the worst school shootings in American history, journalists sought answers Thursday from police about a basic question: What happened when an 18-year-old carrying a gun showed up at Robb Elementary School on Tuesday?

Many said they left the news conference more confused than before.

Texas Department of Public Safety official Victor Escalon Jr. appeared to lack basic information about the initial police response and why officers waited at least an hour before entering the classroom where the gunman holed up during the attack, which left 19 students and two teachers dead.