Baltimore police have arrested more than 20 people during a protest after participants blocked lanes on an interstate in the city.

Lt. Jarron Jackson, a police spokesman, says some protesters blocked traffic on Interstate 83 on Saturday. He says arrest numbers are preliminary.

Video on social media posted by observers showed people forming a double line with their arms linked across the road. Many participants appeared to be young adults.

One participant wore a shirt that said "I am Freddie Gray." Gray was fatally injured in the back of a police van last year, prompting protests and rioting.

Organizers said they were rallying to create a civilian review board for police investigations. They also want to reallocate 10 percent of the city's police budget for community programs.