Protesters mass after another police shooting of black man in US

A protestor is detained by NYPD officer as people take part in a protest against the killings of Alton Sterling and Philando Castile during a march along Manhattan's streets in New York July 7, 2016.

The protests were peaceful but tension was evident after the shooting of Philando Castile, 32, by police near St. Paul late on July 6. His girlfriend posted live video on the internet of the bloody scene minutes afterward, which was widely viewed.

Castile’s death occurred within a day of the shooting of 37-year-old Alton Sterling in Baton Rouge, Louisiana. Sterling was killed during an altercation with two white police officers. Graphic video of that incident caused an outcry on social media.

In Chicago, protesters shut down a stretch of the Dan Ryan Expressway - one of Chicago's main arteries - for about 10 minutes on July 7.

In New York, several hundred protesters blocked traffic in Times Square in the heart of Manhattan, chanting "Hands up, don't shoot." Police eventually cleared the intersection of 7th Avenue and 42nd Street to let traffic proceed.

In St. Paul, about a thousand people gathered outside the governor's mansion, chanting "Hey hey, ho ho, those killer cops have got to go," and other slogans.

Minnesota Governor Mark Dayton made a brief appearance in an attempt to quell the crowd. Earlier in the day, he said a state investigation was already under way.

Dayton called for the U.S. Department of Justice to open its own investigation, but the department said on July 7 it would assist the state investigation as necessary. The Justice Department has opened an investigation into the Baton Rouge shooting.