An army trainee boarded the bus in South Carolina on Thursday (6 May), before pointing a rifle at the driver and ordering him to drive to the next town.
He also ordered all 18 pupils on board the bus to the front - though this proved to be a mistake.
Speaking at a press conference, Richland County Sheriff Leon Lott said the children started 'frustrating' the gunman by overwhelming him with questions.
"The kids were asking questions. 'Are you gonna hurt us?' 'Are you a soldier?' 'Are you a bus driver?' So they were being kids, they were being kids," Lott said.
"I think that added to the frustration that he had."
Six minutes later, the gunman let everybody off the bus, before driving a short distance and exiting the bus himself.
Lott added: "There was six minutes, six minutes, they were traumatised. Six complete minutes that the bad guy was on the bus with a gun."
The suspect has been named as 23-year-old Fort Jackson military trainee Jovan Collazo, from New Jersey.
He has been charged with 19 counts of hijacking, as well as a number of other charges, including car jacking and armed robbery.
Lott praised the bus driver for how he handled the situation.
He said: "I'll give the bus driver credit. He kept his cool. He didn't overreact. He didn't get excited. He kept his cool enough that kept the situation calm.
"And I will tell you his main concern was the safety of those kids."
Brigadier General Milford Beagle Jr, the Fort Jackson base commander, said he believed the suspect was overcome with homesickness, prompting him to scale a tall fence and flee through a wood before he hijacked the bus.
According to NBC News, he said: "As he left the bus, one thing he was trying to do... was trying to acquire new clothes and a ride, which we assume would have been to a bus station, the airport, train station in order to make it home.
"There is nothing that leads us to believe - through his counselling, through anything in his screening records coming in - that this had anything to do with harming others, harming himself."
Fortunately, nobody was harmed in the incident.
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