A Belgrade teenager who was seriously injured in Saturday night’s haunted hayride crash that killed an Oakland teenager and injured 22 others has been released from Boston Children’s Hospital, according to relatives.

Connor Garland, 16, was released from Boston Children’s Hospital, according to a post Thursday night on the “Help the Garland Family! Messalonskee Strong!” Facebook page by his aunt, Valerie Belknap. Previous posts on the site said Garland suffered a broken jaw and injury to part of his back in the accident, and he underwent surgery Monday and Tuesday.

The family is “so excited to report that Connor has left Boston Children’s Hospital! Another step in the process of healing! Thank you everyone for all of your prayers and positive thoughts,” Belknap wrote on the Facebook page.

Saturday night’s hayride accident at Harvest Hill Farms in Mechanic Falls — which killed 17-year-old Cassidy Charette of Oakland, Garland’s girlfriend — is still under investigation by Maine State Police.

Police have said the focus of the investigation is on the 1979 Jeep CJ5 that was towing the hayride trailer, which was loaded with 23 people. The Jeep lost control down a long, steep hill and crashed into trees, throwing off the driver and all passengers. Investigators have said it appears likely that a mechanical malfunction caused the vehicle’s brakes to stop working, but have not said why.

Maine Department of Safety spokesman Steve McCausland said Thursday night that the investigation is still continuing and the Jeep is impounded by state police.

“The Jeep has not yet been inspected,” McCausland said. “And interviews are continuing.”

Garland, a baseball player at Messalonskee High School in Oakland, posted on his Facebook page Wednesday night that he was thankful for the time he had with Charette, saying they started dating on Aug. 16.

“I will miss you more and more every day. Everyone loves and misses you,” Garland wrote. “I will see your beautiful smile again some day.”

Earlier Thursday morning, Belknap had posted on the Facebook page that the Garlands “want everyone to know how grateful they are for everyone’s continued love and support, but they are nowhere near ready to speak to the media.”

“Connor has a lot of physical and emotional healing to do before they even consider it,” Belknap wrote.

Sarah Webster, a Charette family spokeswoman, said Thursday night she had not yet heard of Garland’s release from the hospital and that the Charette family did not want to comment.

Since the accident, the Messalonskee community has gathered at several events — sports games, a fundraiser and candlelight vigil — to show support for Charette, Garland, and the others injured. Students collected donations for Garland’s family and held a 50/50 raffle to benefit the Class of 2016 Project Graduation, the Cassidy Charette Scholarship Fund and the Garland family.

At a vigil Tuesday night, a crowd of more than 100 gathered at Mount Merici Academy in Waterville. Charette was a former Mount Merici student and Messalonskee High School junior. She was a three-sport athlete, participating in soccer, indoor track and lacrosse.

Charette was an excellent student at Messalonskee, ranking first in her class of 224 students, according to her obituary.

“She thrived in the academic environment and welcomed challenges,” according to the obituary. “Cass was a leader among her peers and exemplified true character in the way she lived her life. She loved soccer, from her first game at age 5, coached by her dad.”

A memorial service is scheduled at 1 p.m. on Friday at the Thomas College gymnasium in Waterville. A funeral Mass for Charette will be held Saturday at Notre Dame Church in Waterville.