Heidi Overmier's colleagues at Kennywood knew that the petite, single mother with the can-do attitude had been taking a dance aerobics class at LA Fitness in Collier.

So as sketchy details began to emerge Tuesday night about a mass shooting there, they began to worry.

Heidi Overmier

"A number of us all had the same thought last night when we heard this on the news: 'We sure hope Heidi is not there,'" said Ms. Overmier's boss, Keith Hood, marketing director at Kennywood, where Ms. Overmier was director of school sales.

One friend after another tried to reach her by cell phone.

"When we got the phone out of her car this morning, we got seven or eight text messages: 'Heidi, are you OK?' They knew she went to that class. 'I hope you're at Bible study, not the gym,'" one of Ms. Overmier's sisters, Connie Moneck, said.

But Ms. Overmier, 46, was at the gym, where she became one of three women killed by gunman George Sodini.

Her brother, James Stapf, 48, of Rillton, said he learned of the shooting Tuesday night on TV and decided to call his sister.

"Her son answered the phone, and I asked to speak to her, and he said, 'She's down at the fitness club,'" Mr. Stapf said. "I said, 'Are you joking with me?' "

A neighbor whose husband is a police officer at a local suburban department had been at the scene and relayed the news that Ms. Overmier's light blue Saturn Aura was in the parking lot, the family said.

Several grieving relatives gathered at Ms. Overmier's two-bedroom ranch home in Collier yesterday morning.

"Of course there's anger. Not so much anger, just total can't comprehend why someone would do this to perfectly innocent people," Ms. Moneck, 52, said. "It was just totally random."

Ms. Moneck, her daughter, Lindsay Bard, and Mr. Stapf recalled a winsome woman with a sweet voice, a former cheerleader who stood 5-feet-1, and a devoted soccer mom who ferried her 15-year-old son, Ian, to practices.

"She loved her family and she loved Ian. That was her world," Ms. Bard, 29, of Dormont, said. "She's so sweet, the sweetest voice, she'd do anything for anyone."

Ms. Overmier was also active in the First United Methodist Church of Bridgeville, where she attended classes and produced the annual children's Christmas play, writing original scripts and sewing costumes.

Ms. Overmier grew up in West Mifflin and graduated from Penn State University in 1986 with a bachelor's degree in recreation and parks.

She worked in several states in tourism and the hotel industry before returning to Western Pennsylvania in a job with Kennywood. The amusement park was close to Ms. Overmier's heart. Her family said she had worked there since high school. The park's general manager, Jerome Gibas, actually worked with Ms. Overmier about 25 years ago. He was full time, and his now-wife and Ms. Overmier were seasonal employees.

Ms. Overmier joined Kennywood full time in 1998.

"I was so impressed with Heidi, with her smile and her attitude that 'I can do this, I can get this done,' and her background fit very nicely," Mr. Hood said. "I knew she was going to be good. I don't think I realized how good she was going to be at the time."

Ms. Overmier was in charge of ticket sales to schools, ticket printing and booking bands for the annual fall fantasy parade, which begins next week.

She also operated the electronic billboard along state Route 837 outside the park.

"It took us a while to figure out how to put up a message," Mr. Hood said, "and the message simply says, 'We will miss you, Heidi.'"

In addition to her son, Ms. Moneck and Mr. Stapf, Ms. Overmier is survived by her mother, Joy Jordan, of North Versailles and sisters Leah Masar of Munhall and Terry Schuchert of North Huntingdon.

Visitation will be from 1 to 4 p.m. and 6 to 9 p.m. Friday at William Slater II Funeral Home, Greentree Road, Scott. The funeral service will be at 10 a.m. Saturday at the Bridgeville United Methodist Church, Station Street.