Protests after US police filmed holding black man down and shooting him in chest

Peaceful protests have been held across the US after a black man was filmed being pinned to the ground and shot in the chest by two white US police officers in Louisiana, on Tuesday.

The footage has sparked protests and social media outcry over the latest case of alleged police brutality against African-Americans.

Several arrests were made in Philadelphia, Pennsylvania, after a group of protesters blocked a ramp off a highway.

The arrests were peaceful and there were no confrontations between police and protesters.

Alton Sterling, 37, was killed outside a shop in Baton Rouge, on Tuesday morning.

Videos of the altercation appear to show Sterling being held down and shot several times.

• Warning: Some may find this video disturbing

It is being reported that a law enforcement official, speaking on condition of anonymity, said a gun was taken from Sterling after he was killed.

A witness has also alleged to have seen police pull a gun from the man's pocket after the shooting, but it was unclear whether he had the gun in his hand or was reaching for it when he was shot.

Abdullah Muflahi, who filmed the fatal encounter, said he was "heartbroken", saying his video proved Sterling posed no threat to the officers.

"I'm heartbroken. It's outrageous. It's crazy," said Muflahi, who considered Sterling a friend and allowed him to sell CDs outside his store.

Several hundred people gathered on Wednesday to protest near the spot where Alton was fatally shot, whilst #AltonSterling was among the top trends on Twitter.

Protesters chanted "Hands up, don't shoot" and "Black lives matter."

The Justice Department has launched a civil rights investigation into the killing.