A Mundelein teenager who died after being found unresponsive at Lollapalooza suffered a seizure, his mother said Monday.

“We only know that he had a seizure and that his heart stopped because of the seizure,” Evan Kitzmiller’s mother, Melissa Kitzmiller, told the Chicago Sun-Times Monday.

About 7:50 p.m., 16-year-old Evan was taken to Northwestern Memorial Hospital, where he was pronounced dead nearly an hour later, Chicago police and the Cook County Medical Examiner’s Office said. An autopsy Monday didn’t rule on the cause and manner of his death pending further investigation.

Kitzmiller said she last heard from her son about 6 p.m. Sunday, when he texted her, saying, “Going fine.”

Then, later, she received a “very confusing” call from someone at a medic tent at the music event. She said her son didn’t have an identification with him.

“They said they believed it was our son, but they weren’t sure,” she said.

It wasn’t until about 11:30 p.m. when her son’s identity was confirmed, she said.

Kitzmiller said this was her son’s first Lollapalooza. He’d been going every day by train from Mundelein, returning home at night with his friends.

“It was all his favorite artists there and he was having a blast,” said his mother.

Kitzmiller said her son had “tons of friends.”

“He loved playing video games and listening to music,” she said. “He was a good kid.”

Evan was an honor roll student at Mundelein High School, according to Ron Girard, a school spokesman.

He was headed into his junior year. He had played football, basketball and baseball as a freshman but didn’t participate in sports as a sophomore, Girard said.

The medical examiner’s office hasn’t ruled on a cause of death. Police are conducting a death investigation.

Contributing: Mitch Dudek, Sun-Times Wire