alton towers crash
Crews from the West Midlands Ambulance Service rescuing those trapped on the Smiler rollercoaster at Alton Towers Resort where two carriages crashed today on June 2, 2015 in Alton, England. Four teenagers have have been seriously injured. West Midlands Ambulance Service

A law firm offered an apology over a distasteful tweet promoting its services following the Alton Towers rollercoaster crash. The park is to be closed until a full investigation into the accident has been completed.

Shortly after two carriages collided on The Smiler rollercoaster at Alton Towers seriously injuring four teenagers, the Broad Yorkshire Law firm tweeted saying they're "expert" in personal injury.

The result was an outpour of criticism over social media.

The company later deleted their comment from Twitter and posted an apology.

Sixteen people were riding a carriage when it collided into an empty stationary carriage just after 2pm on Tuesday (2 June).

The passengers remained stuck 25ft in the air at a 45 degree angle for over four hours before fire service, paramedics and ambulances came to their rescue.

All the trapped injured riders have now been taken off the ride.

While an Alton Towers spokeswoman confirmed "there will be full investigation," Nick Varney, chief executive of Merlin Entertainments that runs the park called the crash a "dreadful incident".

Eyewitness Ben Richardson said: "When the second carriage crashed people were screaming and shouting - even after it stopped. Everyone around the park ran over.

"The people looked significantly distressed. It was almost like a car crash, very full-on."

According to the director of Alton Towers Resort, Ian Crabbe, the incident is the worst in the park's history.

The Smiler that opened in 2013 is known to be the only 14 looping rollercoaster in the world and holds the record for the most inversions.

Meanwhile, Alton Towers park will remain closed.

Nick Varney, chief executive of Merlin Entertainments, which runs the park, said: "This has been a terrible incident and a devastating day for everyone here.

"I would like to express my sincerest regret and apology to everyone who suffered injury and distress and to their families.

"The safety of our visitors is our primary concern. The park will remain closed until we understand better the cause of this dreadful incident."

Alton Towers crash
Emergency services work at Alton Towers Resort where two carriages crashed on June 2, 2015 in Alton, England.The West Midlands Ambulance Service said of the 16 on the ride, four had serious leg injuries. Getty Images