By RENÉE C. LEE
Copyright 2010 Houston Chronicle
April 12, 2010, 11:15PM

Four-year-old Samantha Sillero loved riding horses with her parents, and she never had any problems with the animals until the fatal accident over the weekend at a rodeo event, family members said Monday.

Samantha died after being trampled by a horse. The accident happened at a rodeo arena in the 13700 block of Karalis in south Houston around 10:35 p.m. Sunday, police said.

Samantha and her mother, Mary Sillero, were riding their family's horse in the parking lot when the animal became ill and began acting out of control, said the girl's cousin, 22-year-old Maria Sillero.

She said family members told her that the horse began banging its head against a car and threw both riders, then stepped on the girl's head.

The girl's father, Sergio Sillero, who had gone to the stables to return a horse, arrived just as the accident happened, Maria Sillero said.

The mother and daughter were rushed to Memorial Hermann Hospital, where Samantha was pronounced dead about 11:15 p.m. Mary Sillero, who suffered bruises, was released Monday morning.

The Harris County Institute of Forensic Sciences, which conducted Samantha's autopsy, listed the cause of the death as blunt head trauma. It's unclear what's going to happen to the horse.

Family members crowded the family's southeast Houston home Monday to console each other. Sergio Sillero and his wife were too distraught to talk about their daughter or about what happened.

Maria Sillero described Samantha as a happy girl who was excited about going to kindergarten in the fall. Maggie Sillero, 14, said her half-sister also loved the color pink and the Disney princesses, which decorated her room. “She was really sweet and shy at times,” Maggie said. “She loved to communicate and was learning the alphabet.”

renee.lee@chron.com