OAKLAND — Police on Tuesday arrested a 16-year-old Oakland High School student suspected of lighting a man’s skirt on fire aboard an AC Transit bus Monday night, causing second- and third-degree burns, police said.

The victim, 18-year-old Luke Fleischman, was in stable condition Tuesday at the St. Francis Memorial Hospital burn unit in San Francisco, his mother Debbie Fleischman said. He is going to require massive skin grafting and a long recovery period, she said.

A fundraising page for Fleischman, who also goes by the name Sasha, was set up Tuesday by his cousin in an effort to raise $10,000 toward his medical bills. Supporters had donated nearly $2,000 as of Tuesday night. The page can be found at http://fundly.com/helping-sasha-fleischman-have-a-speedy-recovery.

Fleischman was apparently asleep on the bus, heading home to East Oakland, when the suspect set fire to a skirt the victim was wearing, his mother said. The victim, a senior at Maybeck High School in Berkeley, does not identify as male or female but rather as nonbinary gender, an umbrella term covering any gender identity that does not fit within the gender binary.

“My son considers himself agender,” Debbie Fleischman said. “He likes to wear a skirt. It’s his statement. That’s how he feels comfortable dressing.”

She said her son has been riding the bus home from school, oftentimes wearing a skirt, for the past year and has not had any problems or threats.

Police investigators are still sorting out a motive, but Debbie Fleischman said she is torn about whether the fire was a prank or a hate crime. “It’s something I’m worried about,” she said.

She said her son told her and his father, Karl Fleischman, about two years ago that he did not want to identify as a man or a woman. He also became politically involved in the issue of nonbinary gender, gathering 27,000 signatures on the Internet in hopes of catching President Obama’s attention to the subject.

Police said the attack happened about 5:20 p.m. Monday on an AC Transit 57 line bus with at least a dozen passengers on board. The bus was heading eastbound on MacArthur Boulevard near Ardley Avenue.

Police said it appears the suspect, a junior at Oakland High School, boarded the bus near the school and saw Fleischman sleeping in a rear seat and lit his skirt on fire.

When the victim woke up, he tried unsuccessfully to put out the flames himself. Other passengers rushed to his aid and extinguished the flames, which severely burned the man’s legs.

The bus driver did not immediately realize what had happened but stopped the bus a short distance away when he became aware of the attack, police said. Everyone, including the suspect, then got off the bus.

The suspect was detained on campus Tuesday afternoon and taken away by Oakland police, said Oakland Unified School District spokesman Troy Flint. He was arrested on suspicion of assault with a deadly weapon and mayhem and could face other charges, said Officer Anwawn Jones, the lead investigator on the case Police said the 11th-grader was identified through surveillance video on the bus. They did not say whether the victim and suspect knew each other.

Anyone with more information may call police at 510-238-3426, a tip line at 510-773-2805, or Crime Stoppers at 510-777-8572.

Staff writer Natalie Neysa Alund contributed to this story. Reach Kristin J. Bender at kbender@bayareanewsgroup.com. Follow her at Twitter.com/kjbender. Reach Harry Harris at hharris@bayareanewsgroup.com. Follow him at Twitter.com/harryharris15. Contact David DeBolt at ddebolt@bayareanewsgroup.com. Follow him at Twitter.com/daviddebolt.