Four people are in critical condition Thursday after they were struck by a pickup driver in MacArthur Park.
Los Angeles police said the man was trying to drive away from officers who were going to ask him to move his truck. They initially said officers were going to issue the man a ticket.
Aerial video showed a Dodge Ram pickup stopped on a sidewalk in the park.
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Police said the man stayed at the scene, cooperating with investigators. He was taken into custody.
The hospitalized victims were identified as men, ages 24 to 35. Two were in critical condition.
Authorities have not determined whether the driver lost control or suffered a medical emergency behind the wheel.
A woman who said she is a friend of the driver identified him as Rofino Ariston. She says he is homeless and lives with his dog in his truck.
"All I can do is wish the best for him. Hopefully the people are OK," Justyna Sawicka said.
His friend believe Ariston would not have done it on purpose.
At least seven Los Angeles Fire Department vehicles responded to the location in the 900 block of Park View Street. Yellow police tape blocked off an area near the sidewalk, apparently the site of the crash.
The park in the Westlake neighborhood northwest of downtown Los Angeles is divided by Wilshire Boulevard and features a lake, amphitheatre, children's playgound and soccer fields.