Parents of a 7-year-old boy with special needs are pressing for answers, unable to shake images of the long hours he allegedly spent alone strapped in a school bus Thursday after being picked up at his north Minneapolis home.

Lasandra Parker and Steve Berglund say the day began like any other, with the yellow short bus rolling up to their house Thursday about 8:20 a.m. to get Miles, who has autism spectrum disorder and is nonverbal.

But Miles, they say, never made it inside Jenny Lind Elementary School at 5025 Bryant Ave N. that morning.

Instead, they say, he was left strapped in his seat as the bus, operated by the Metropolitan Transportation Network, returned to its garage. It was there that someone spotted Miles about 2:15 p.m., according to his parents.

Parker said she can't imagine how her son endured Thursday's heat or being pinned down by the seat belt for more than five hours. Miles, she said, doesn't like being strapped down for car rides that last longer than 15 or 20 minutes.

"He gets hysterical," Parker said Friday. "He could have very well harmed himself or just died of heat stroke."

The boy's parents say they are haunted by unknowns and incensed at the lack of clarity from the school district and bus company.

They say Miles is always unbuckled by an aide and is walked to his teacher, raising questions about how he was overlooked.

"He's very vulnerable," Parker said. "How did you forget my child? Why was the bus not checked before they dropped it off?"

Berglund, Miles' dad, said family should have been alerted immediately, along with 911, as soon as Miles was found and taken back to the school. "I'm outraged and hurt and my trust is broken," Berglund said. "I've heard literally a million apologies but not one answer."

Minneapolis Public Schools said in a statement Friday that it is investigating the incident. District officials say standard procedure is for bus drivers "to check for children on the bus before exiting."

"The idea of any child being left unattended on a bus is absolutely unacceptable," the statement read. "We are confident our investigation will determine the facts of this particular report."

Berglund and Parker say they are thankful their son is safe but won't rest until they understand what happened.

"There is really no way he should be alive," Berglund said. "No other child should go through what Miles went through."

In a statement Saturday, the bus company said it is investigating the incident and that it had apologized to the student and his custodian Thursday.

The company has procedures to keep students from being left unattended on idle buses, the statement said. "The investigation is intended to uncover what, if any, specific employee lapses resulted in the student's presence on the bus being overlooked."

A company official said, "We are doing everything we can to ensure that these types of situations do not occur in the future."