A man has been arrested on suspicion of careless driving and remains in custody.
Police were called at 6.48pm and the South East Coast Ambulance Service and Kent Fire and Rescue Service also attended the scene.
Footage posted on social media showed a trail of destruction as dozens of badly damaged cars and debris were strewn across the street.
A total of 14 people were walking wounded and received treatment at the scene.
Kent Fire and Rescue said one person required oxygen following the incident.
Oliver Monahan, area managing director for Arriva Kent and Surrey, said: "Arriva can confirm that a bus has collided with a number of vehicles on Hythe Street in Dartford on Tuesday evening.
"There have been some reported injuries and at the moment our priority is supporting the emergency services.
"Our thoughts are very much with all those affected."
The road is closed while recovery work is ongoing but is anticipated to be re-opened later on Tuesday evening, police said.
Brian Barnett tweeted: "Serious accident in Dartford, my car smashed!"
He told Sky News he was in his car when the collision happened.
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