CELINA, TX-A Celina parent is in trouble with the law for conducting his own drill to test school security.

Ronald Miller was arrested for making a terroristic threat after police said he walked up to Celina Elementary School Wednesday, told staffers he had a gun and asked them what they'd do about it. Miller was unarmed, but school officials said he continued to aggressively question school security which led them to call police. But parents said they weren't notified until Thursday, the superintendent tells us why.

"I'm very angry. Our kids could have easily been killed over there. I know he didn't have a gun and didn't happen but if they thought it was enough of a threat to call 911, the cops, to begin with, they should have thought enough to lock it down, whether they thought something would happen or not."

Diana Wilson couldn't believe Celina I.S.D. didn't notify parents until a day after Ronald Miller walked into Celina Elementary School claiming to have a gun and asking staff how they'd protect the kids.

Celina Superintendent, Donny O'Dell said they knew who Miller was and that he did not have a gun.

"We did not go into lockdown yesterday because basically none of our kiddos were at risk and they were all safe and the person was gone before the risk arose," he said.

Celina Police Sgt. Shea Scott said around 7:50 Wednesday morning, Miller walked into the elementary school telling staff he was a shooter to test the school's security system. Sgt. Scott said Miller was arrested for making terroristic threats, a felony crime.

"It did cause fear and panic within the school staff and from that going into a situation where you intend to cause some type of reaction. That does constitute a terroristic threat especially in a school," he said.

O'Dell said they did not tell parents about the incident until Thursday because they don't want to interfere with the investigation.

"We have taken a big black eye over this particular situation, but yesterday morning when we were trying to sort things out, we made the decision at that time not to release anything until the police had finished their work," he said.

O'Dell said Miller was well known to parents and students who attend the school that's why he was allowed to enter. But now, they won't make any exceptions.

"Anybody can be that particular person. I mean this person was a parent and he's somebody that people on the campus knew and they trusted," he said.

O'Dell said the district plans to add security cameras and will now buzz-in visitors once they're approved.

We went to Miller's house, his wife told us they have no comment. O'Dell said Miller will not be allowed on Celina school property for the remainder of the year or longer because of the incident.

Miller was released on bond Thursday from the Collin County Jail.