Two police officers have been shot at a July 4 fireworks display in the US, and crowds of people can be seen running for their lives with a "active" gunman on the loose.
Police helicopters can be seen flying over the Welcome America concert in Philadelphia and there are a large number of emergency service vehicles by the Art Museum.
It comes in a night of gun violence in the US with a Fourth of July massacre in Chicago. There was also a stampede at a fireworks display in Orlando, where there were false alarms of gunfire, leading to 12 injuries.
One minute people were enjoying fireworks and a concert at a July 4 celebration and then the next they were running for safety at an event on the Benjamin Franklin Parkway.
People at the concert have told local media how police shouted at them to "run and don't look back".
"Chaotic scenes, a lot of people are upset, fireworks going off, police coming from everywhere," said news outlet CBS3.
"We can hear a search helicopter, police say they are still searching for a suspect. Scene went from fireworks to shots being fired."
Two police officer have been shot but are in a stable condition in Jefferson University Hospital.
"There is a security incident on the Benjamin Franklin Parkway. Please follow public safety instructions and avoid area. Details to follow," tweeted Philadelphia Police.
Adding: "For those looking to reunite with loved ones on the Parkway, please meet at 1901 Vine Street in front of the Free Library of Philadelphia. All others, please avoid the area."
There had been a massive police presence around the fireworks display including scans for weapons on the Ben Franklin Parkway.
But the shooting took place around 9.45pm on the 2500 block of Spring Garden Street.
The shooting led to hundreds of people running along the Ben Franklin Parkway and away from the concert and fireworks.
"Police tell me both officers wounded in shooting are in STABLE condition at Jefferson. An officer assigned to Montgomery Co. Bomb Squad was shot in shoulder, Highway Patrol Officer has a graze wound to the head," tweeted a CBS3 journalist.
Traffic is being diverted from the area and police have started a manhunt for the shooter.
Another person tweeted: "Fireworks have stopped. Crowds are leaving and officers were running toward the Art Museum. Police helicopter circling. No confirmation of what happened yet."
It follows a Fourth of July massacre in Highland Park, Chicago, were a gunman has killed at least six people and injured around three dozen other.
Robert E Crimo III, who is suspected of carrying out the attack was finally caught after a police manhunt. He is now in custody where he is being treated as a "person of interest".
