A Clovis teacher used his darkened, empty classroom to take video of a blindfolded second-grade girl giving him oral sex in what he called "the lollipop game," a federal investigator says.

The disturbing accounts and videos, dating as far back as Jan. 3, came to light after the victim's mother became suspicious because she could not see her daughter outside with the rest of her class in physical education at Freedom Elementary School last Thursday.

The girl's teacher, Neng Yang, 43, also was not with his class.

By 5 a.m. Saturday, he was in jail. Yang made a brief appearance Monday in U.S. District Court in Fresno, where he pleaded not guilty to a charge of producing child pornography.

Yang's arrest shocked parents at Freedom Elementary, a newer school at the northwest corner of Gettysburg and Locan avenues. He had been a teacher there since 2007, and some parents interviewed Monday said he had been considered a good teacher. Now, some parents are questioning whether their children may also have been abused. Clovis police said no other victims have come forward, but detectives were fielding many calls Monday.

Tony Varni's fourth-grade daughter had been in Yang's class in second grade. "I'm absolutely, 100% stunned" by the arrest, he said Monday afternoon as he waited to pick up his daughter from the school.

"She used to help him after school," Varni said. "She's pretty taken aback."

Although his daughter says Yang never harmed her, Varni said he still worries. "We're just trying to get through this. I'm not sleeping, but we're praying," he said.

Parent Kao Lee said she worried that Yang's arrest would hurt community perceptions of the Hmong people.

"I'm Hmong, he's a Hmong teacher. It's a setback for us," said Lee, who has a child in another second-grade class. "I have cousins who had him at another school. They said he was a good teacher.

"You have to trust people with your children, but you can't watch them 24 hours a day," Lee said.

Mailee Thao, whose second-grade child was not in Yang's class, said she was saddened by his arrest. "He had a reputation for being a wonderful teacher. Most people I know were looking forward to their children being in his class."

School officials met Sunday with parents of students in Yang's class. On Monday evening, officials held a closed-door meeting that drew hundreds of parents of students at the school.

District officials provided parents some details of the investigation, and Clovis police detectives were available to talk privately with parents who might have more information about Yang.

"The severity of this situation is unlike anything our district can remember," Clovis Unified spokeswoman Kelly Avants said Monday night.

Parents also were given a handout with suggestions on how to discuss what happened if their children ask questions. Among the suggestions: "If your child asks questions, provide him or her with information in an age-appropriate way. Let your child's questions guide you. Avoid sharing information which your child hasn't asked about."

After the event, many parents expressed the range of emotions on display during the session, from anger and anxiety to sadness.

"Before the meeting, I was at the point that I thought I needed to get my kid out of here," said Natalie Torres, whose son attends kindergarten at Freedom Elementary. "I got the answers I was looking for, but I'm still upset."

And Torres was still wary.

"I couldn't believe they said that 'everyone on staff can be trusted' after this," Torres said. "That trust issue will be in the back of my mind, no matter what school my son goes to."