People fighting for life after truck crashes into pedestrians in US

At least six people were injured after a box truck struck pedestrians in downtown Boston in the US, authorities said.

Those injured include two people in critical condition, two people with non-life-threatening injuries and two people who were treated at the scene, a law enforcement source familiar with the investigation tells CNN.

Investigators believe the truck crash is an accident, the source told CNN.

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Around 12.48pm Tuesday local time (3.48am Wednesday AEDT), "officers responded to a radio call for a motor vehicle accident with pedestrians struck at the intersection of Harrison Avenue and Kneeland Street," Boston Police Officer Michael Torigian wrote in an email to CNN.

"Upon arrival, officers observed a truck that appeared to have struck a nearby building as well as an unknown number of pedestrians. Boston Fire and EMS are on scene assisting in rescue efforts. This is a very active scene and does not have a total number of victims yet. At least two are critical and homicide and the fatal accident team are responding."

Aerial footage showed a Penske truck on its side, wedged between a pole and a building, with the cab smashed.

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The truck was being rented out to a commercial trucking company, Penske said in a statement.

The company said it plans to cooperate fully with investigators.

"Our thoughts are with those who have been injured in this unfortunate incident," Penske's statement read.

The areas of Harrison Avenue and Kneeland Street between Tyler and Washington streets are closed as police work the scene.

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