It was supposed to be a fun outing for the 3-year-old twin boys, but a ride on a roller coaster at an indoor amusement park in northwest suburban Norridge proved fatal.

Jayson Dansby, 3, was killed Saturday night at Go Bananas while riding a children’s roller coaster called the Python Pit, authorities said.

The boy, who was seated near the front of the roller coaster with his twin brother, managed to get underneath the safety bar of the roller coaster and slip out of the ride while it was in motion, Norridge Police Chief James Jobe said. The boy fell between two cars and suffered head injuries, then fell a few feet to the floor.

It is believed the boy met all the requirements for the ride, Jobe said.

Jayson, of the 15300 block of Evers Street in Dolton, was dead on the scene. An autopsy performed Sunday found that Jayson died of multiple injuries after he was struck by the roller coaster car and fell from it, according to a spokesman for the Cook County medical examiner’s office. Jayson’s death was ruled accidental, the spokesman said.

On Sunday, Jayson’s family gathered to mourn the boy and remembered him as loving and friendly.

“”He was a fun child. … That child had more spirit and joy than anything in the world,”” Jayson’s great-uncle the Rev. Carl Jones told reporters. “”I want to remember the joyous times, the love times, not the incident that took place. I need to remember what time I spent with this child.””

Jones said the family was on an outing to the amusement park.

“”They were celebrating life,”” Jones said. “”It was just a day out with the kids.””

The indoor amusement park for children has been open about six years, owner Jerrold Marks said Sunday.

“”I just want to say how tragic this is and how bad I feel for the family,”” he said. “”We’re going to 100 percent cooperate with all the various authorities in the investigation.””

He declined to speak about the incident or the roller coaster.

The Illinois Department of Labor, which regulates carnival and amusement park rides, dispatched an investigator to Go Bananas immediately after the incident, spokeswoman Anjali Julka said. She declined to speak specifically about the current investigation.

Meanwhile, neighbors in the tight-knit Dolton neighborhood lined with neat brick homes mourned Jayson on Sunday.

“”I called him ‘Mr. Jolly,'”” said Trina Young, 43. “”I’m going to miss him. He was like a part of my family.””

As friends and family arrived at the Dansby home, one woman turned to reporters and said: “”They’re up by one in upstairs,”” as she pointed to the sky.

Tribune reporter Andrew L. Wang contributed.