By CBSLA Staff

LOS ANGELES (CBSLA) — Police made an arrest in a Chinatown hit-and-run that severely injured a 70-year-old woman, and now they need help tracking down a witness to the crash.

Tips led to the identification of the suspected driver after Los Angeles police officials released security video of the Sept. 4 crash at North Broadway and College Street. Detectives arrested 24-year-old Christopher David Smith at his home in Menlo Avenue Friday.

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Smith has since been released after posting $50,000 bail.

The elderly woman was crossing North Broadway in a crosswalk with a “Walk” signal when she was struck by a black Mercedes-Benz sedan making a left onto Broadway from westbound College Street. The woman was thrown several feet into the air and landed on the street. She remains hospitalized in critical condition.

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(credit: LAPD)

Video taken from inside a pharmacy on the corner show several people came to the woman’s aid, including one that police now say they are hoping to question further.

“Trying to locate this female in the white top, blue shorts,” LAPD Detective Juan Campos said in a tweet.

The woman was seen kneeling over the victim and waving for help.

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Anyone who knows the woman, or has information about the crash can contact Detective Campos at (213) 486-0755 or via email at 31480@LAPD.Online.