Texas Ranger Victor Escalon. [Source: BBC]
A gunman who attacked a primary school in Texas on Tuesday was able to enter the building unobstructed.
Texas Ranger Victor Escalon says no armed guard challenged the teenage attacker and it is unclear if the school door was even locked.
Escalon defended the police response amid mounting criticism of an apparent delay in confronting the gunman.
Reports quoted witnesses saying police were hesitant to confront the killer inside the School.
Escalon says initial reports the gunman had shot a guard were incorrect.
He says officers entered the school four minutes after the gunman went in at about 11:40.
But an hour elapsed before the gunman was killed in a shootout at 12:45 only after US Border Patrol tactical teams arrived.
The attacker shot dead 19 students and two teachers and injured at least 17 more people.
Videos have emerged of police being urged by onlookers and desperate family members to storm the building immediately.