A former US Olympian is recovering after being brutally attacked by a pipe-wielding homeless man in downtown Los Angeles.

Kim Glass, who won a silver medal in volleyball in Beijing in 2008, suffered a fractured cheek, bruising to her face, and a large gash over the left side of her nose when she was randomly assaulted as she left lunch with a friend.

The 37-year-old took to social media to describe the unprovoked attack that took place on Saturday.

“As I was leaving lunch, I was outside saying goodbye to a friend and this homeless man ran up. He had something in his hand, he was on the side of the car in the street, and he just like looked at me with some pretty hateful eyes and as I go to tell my friend I think something is wrong with him, before I knew it a big metal bolt-like pipe hit me. It happened so fast, he literally flung it from the street,” she said.

A group of strangers helped her until paramedics arrived at the scene, while others held the alleged attacker down until police could respond.

In a social media video, the athlete’s eye could be seen swollen shut and she said she had suffered a fractured cheek.

“Guys, just be safe out there... I wasn’t ready for it and there’s a lot of mentally ill people on these streets right now,” she added.

An attempt is underway to recall Los Angeles County District Attorney George Gascón, a Democrat, amid claims from his critics that he is soft on crime.

Los Angeles Police Department says that violent crime in the city has risen eight per cent in 2022, while total arrests have fallen by around 12 per cent.