Authorities are investigating what led up to a motorist driving through a red light and into nearly a dozen people as they left a church Christmas event in Southern California — leaving three women dead and several other people injured, including children.

Margo Bronstein was arrested on suspicion of driving under the influence and vehicular manslaughter and was expected to make her first court appearance either Friday or Monday, Redondo Beach police and Los Angeles County prosecutors said.

Authorities said they believed she had taken prescription drugs, but were awaiting the results of a toxicology test.

A message seeking comment left at a phone number listed for Bronstein was not immediately returned, and it wasn't immediately known if she has an attorney.

Officials said they do not have information linking her to any prior arrests or DUI-related incidents.

She had a perfect driving record but was restricted to driving a vehicle with hand-controlled brakes, an additional right-side mirror and adequate signaling device, according to Department of Motor Vehicle records.

The DMV had no record listing her as handicapped, however.

Friends and neighbors said she used crutches at times and a motorized wheelchair at longer distances, but they did not know why.

They said she is always friendly and deferential.

"She's very personable, very kind," Vanecia Wiley, a manager at the senior housing community where Bronstein lives, told the Los Angeles Times. "She doesn't want to be in anyone's way."

Dulce Mojarro, 34, met Bronstein two years ago at Disneyland and said the two would sometimes meet up at the park, which Bronstein loved.

"She is like one of those kids that never wanted to grow up," Mojarro told the Times. "I would tell her, 'You have that child in you like Peter Pan.'"

The pedestrians on Wednesday night had just attended a student Christmas program at St. James Catholic Church when the motorist sped around the other vehicles in a white Saturn sedan and plowed into the crowd before hitting another car head-on, police Lt. Shawn Freeman said.

Five children and eight adults, including the suspect and the other driver, suffered injuries including broken bones, abrasions and head trauma, Freeman said. Three people, Mary Anne Wilson, 81; Saeko Matsumura, 87; and Martha Gaza, 36, all of Torrance, later died, police said.

Alan Wells, who lives in the apartment building at the corner, heard the crash and ran outside.

"I saw people lying all over the street, and people in the crosswalk were screaming and yelling," he told the Daily Breeze.

One boy who was struck was flung across the intersection, ending up beneath an SUV's tire, according to witnesses.

"The car is on the little boy. And we finally rolled it off the little boy. He had a little tie on. It was scary. It looked like he was in heaven at that point," Michael Tovar told KTTV.