A San Antonio man was arrested Tuesday after a teacher found a handgun in the backpack of the man's 3-year-old child at a San Antonio pre-K center, police said.

An off-duty parks police officer providing security at the center contacted city police officers when the gun was found Tuesday morning, San Antonio police said.

The child's father, Pete Robles, 35, was arrested on charges of child endangerment, and the child was placed in protective custody with Child Protective Services, police said.

Robles was being held at the Bexar County jail. He did not have an attorney listed as of Wednesday afternoon and his pre-trial hearing has been set for September 12, court records show.

"This incident underscores the important collaboration between the school faculty and law enforcement personnel. Swift action was taken to address the situation and make an arrest," San Antonio Police Chief William McManus said in a news release. "There are no current threats to the safety of the school or its students.

"To provide further assurance, (police) will maintain an increased uniformed presence at the school for the foreseeable future."

The investigation into the incident is active and more arrests and charges are possible, police said.