Update - 2.30pm: Kent Police said the 21-year-old man arrested on suspicion of attempted murder suffered minor injuries and was taken to hospital as a "precaution" and he was now currently in custody.
Investigating officer detective chief inspector David Chewter, of the Kent and Essex Serious Crime Directorate, said: "This was a frightening experience for everyone involved and it is a miracle that nobody was killed.
"At least 13 people were hurt but none of their injuries are described as life-threatening or life-changing.
"We believe there are likely to be further casualties who perhaps left the club during the panic and we would like to hear from them."
Update - 11am: A driver who allegedly ploughed his car into a nightclub injured 13 people - leaving several with broken bones, police said.
Kent Police said a 21-year-old had been arrested on suspicion of attempted murder after a vehicle was driven on to a dancefloor at Blake's in Gravesend at around 11.45pm on Saturday.
Detectives believe he had been kicked out of the venue over an altercation.
The force said in an update: "At least 13 people were injured but officers believe several others may have left the scene and are working to establish how many further victims there may be.
"Several of those hurt suffered broken bones but none of their injuries are described as life-threatening or life-changing."
The force added that the episode was not being treated as terror-related.
8.45am: A number of people have been injured and a man has been arrested on suspicion of attempted murder after a car was driven into a nightclub in the UK.
Kent Police say it is believed the driver had been asked to leave the venue following an altercation.
Witnesses described "a complete mess of panic and chaos" in the wake of the incident shortly before midnight on Saturday.
Footage posted on social media showed a large car, headlights still shining, on a chequered dancefloor inside a marquee at the Blake's nightclub.
Watch: Panic as car driven into Kent nightclub pic.twitter.com/eLnoKuq3hc— PA Media (@PA) March 18, 2018
In another clip, security staff appear to surround the driver, and a reveller can be heard asking: "Why did he try and do that?". Another replies: "I'm so confused."
Shocked clubbers spilled out onto the street as emergency services arrived, with footage showing police cars, fire engines and ambulances lined up outside the venue.
Witness Sonny Powar said he saw two people get hit by the car before the driver was pulled from the vehicle.
"(It was) just a normal night out at Blake's Nightclub in Gravesend in Kent," he told the Press Association.
"But some guy wasn't let into the club or got kicked out so he drove his 4x4 into the tent we was all in.
"It stopped at my feet so any further and I could have died, then he reversed up and we all ran.
"We ripped the tent wall apart and got out and called the police.
"It was a complete mess of panic and chaos."
BBC Radio 1Xtra DJ Reece Parkinson posted a video from inside the club on Twitter.
He said in the video: "My god I nearly died, so I'm in this club and this car came through the f****** club.
"A guy who didn't get in drove through the club."
A number of people have been injured after a man drove a car into a nightclub in Gravesend. BBC Radio 1Xtra DJ Reece Parkinson posted footage from the scene. Full story here: https://t.co/tfiabQvOYH pic.twitter.com/syEoscnXKM— BBC South East (@bbcsoutheast) March 18, 2018
Details on the conditions of those injured have not been released and the incident is not being treated as terrorism.
Kent Police said they were called to a nightclub in Queen Street at 11.47pm on Saturday.
The force said: "Kent Police has arrested a man on suspicion of attempted murder after an incident in Gravesend where a number of people have been injured when a car drove into a nightclub building.
"The driver of the vehicle who is believed to have been asked to leave the nightclub earlier that evening following an altercation has been arrested on suspicion of attempted murder and is currently in custody.
"This is not been being treated as a terror-related incident."
Kent Fire and Rescue Service said it had sent two fire engines to the scene to assist the police.
- Press Association and Digital Desk