A man who walked onto the campus of an Arlington elementary school Thursday morning with a loaded gun in his waistband and was injured when it accidentally went off is now facing a criminal charge, police say.

NBC 5 has learned the man, identified by police as 55-year-old Anthony White, was walking toward the front office at Duff Elementary at about 11:45 a.m. when he went to adjust his pants and hit the trigger on a gun tucked into his waistband.

The shot injured White's leg, police said. No other injuries were reported and the man's injuries were not considered life-threatening. White was treated and released from the hospital Thursday afternoon.

Arlington police said they do not believe the man had any malicious intent and that he was there to pick up a child. However, because it is illegal to bring a gun onto school property, White was arrested after being released from the hospital and was charged with unlawful carrying of a weapon in prohibited places.

Crossing guard Gerald Sims said because Thursday was an early dismissal day, his shift started at noon.

"As a lady walked over, told me what happened, she said 911 is going to cover the area. Sure enough, that’s exactly what happened," Sims said. "I saw the guy walk. They helped him from the sidewalk down the stairs and back up, sat on there. He sat on that retainer wall until the ambulance came and took him away."

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The school was placed on a brief lockdown Thursday that was lifted a short time later. The Arlington Independent School District said no threats were made to the school, and all students and staff remained safe during the lockdown.

Keri Stubbe, who has two children who attend Duff Elementary, said she received an alert about the lockdown just before noon.

"So, I ran out of work. I’ll probably get fired, but it’s OK," Stubbe said. "I knew they were in good hands. Just as a parent, automatically assume the worst things. So, you just want to be with them."

Stubbe said she was eventually able to get in touch with her daughter through text message.

"'The teacher said we’re all OK. Everything is fine. Our teachers have [us] in our rooms, and everything’s OK. I just wanted to let you know we’re OK,'" Stubbe recalled her daughter's texts saying. "A lot of weight was lifted but at the same time, her being 11 … she had all kinds of stories and not correct information, so I wasn’t sure if it was on the campus. Was it down the street? Where was it? Was this a parent? A stranger? Somebody trying to get to the school?"

Texas Sky Ranger flew over the school early Thursday afternoon and it appeared students were playing outside and dismissing normally. Thursday is the last day of the school year in the Arlington ISD and elementary schools were dismissed at 12:10 p.m.

Federal law requires states designate school property as gun free zones, making it a state crime to carry a firearm onto school property.

The incident comes on the heels of a massacre at a Texas elementary school earlier this week where 19 children and two teachers were murdered, making it the deadliest school shooting in the state's history.