"He goes, 'Mom, I'm on a bus by myself, and the bus driver and all the kids are gone,' " the mother of Michael Sellars recalled

A Long Island, N.Y., mother said her son was left alone on a school bus for nearly half an hour after he wasn’t dropped off at his home and ended up at the end of the route.

"He was left alone for almost 30 minutes," Natalie Sellars of Uniondale told Newsday of what happened to her child Michael, who was 6 years old at the time of the alleged incident. "What if something had happened to him? What if he had gotten off the bus by himself?"

Sellars said Michael, who is now 7, was left on the bus this past June the day before his birthday, Newsday and CBS affiliate WCBS reported. According to Sellars, the then-first grader and several other students boarded the school bus operated by Guardian Bus Company.

Michael was supposed to be dropped off at a bus stop on Greengrove Avenue, where his babysitter was waiting. But the driver apparently skipped the intended bus stop and dropped off the other children at the next stop, while Michael stayed on the bus since he was unfamiliar with his surroundings, Sellars told Newsday.

She called her son on his emergency cell phone when he didn’t show up at home.

"He goes, 'Mom, I'm on a bus by myself, and the bus driver and all the kids are gone.' I said 'What?' " Sellars told WCBS.

"He put his video on, and said, 'Look, mommy.' Thank God he knows how to do that, because me and his dad trained him," she later said. "All I see is the baseball field and I started to freak out ... I blacked out. I started crying, and I called 911 right away."

School officials located the driver’s home address, where Sellars later found Michael on the bus. She said she didn’t understand why he was left on the vehicle since he had not fallen asleep or laid down and had been sitting up during the ride.

Sellars also told WCBS that she hasn’t received a personal apology from the bus driver or Guardian, and that she asked for but has not yet seen surveillance footage from the bus' dash cam taken the day of the incident.

PEOPLE reached out to Guardian Bus Company on Thursday, Sept. 18, for comment. In a statement shared with Newsday and WCBS, the company, which is based in Oceanside, said: "We sincerely apologize. We have a zero-tolerance policy for a child left behind. It shouldn't happen.”

The company also said that the driver has been fired.

In a statement shared with PEOPLE on Thursday, Uniondale School District Superintendent Dr. Monique Darrisaw-Akil wrote, “The safety and well-being of students is paramount to the Uniondale School District. In compliance with privacy laws and guidelines, the District cannot discuss the particulars of this case.”

Darrisaw-Akil continued, “However, what we can say is that the District took immediate action to ensure the bus driver in question was removed from all future Uniondale School District bus routes. Additionally, all District protocols and procedures were followed in terms of responding to the child's and the family's concerns and needs subsequent to the incident."

As a result of the incident, Michael, who has asthma and didn’t have his inhaler with him at the time, has refused to go on a school bus and is in therapy, Sellars told Newsday.

"At night, he comes into my bedroom and wants to sleep with me, which he’d stopped doing since he was 3," she said. "And when he sees a bus, he goes, ‘Mommy, I don't want to go on that bus.’ He’s too scared to get back on a bus. He’s worried they’ll leave him again."(PEOPLE)