A woman in her 60s was killed and 22 others were injured in a crash between a double-decker bus and two cars, authorities said.
Nineteen people were taken to hospital, including four who were airlifted, after the collision on Forest Road in Newport on Sunday afternoon sparked a major incident.
Hampshire Police said three other people travelling in a red Fiat Bravo with the woman who died at the scene were taken to hospital in a “serious condition”.
The bus driver, a man in his 50s who had to be cut from his cab, was also believed to have been seriously injured, while 10 of his passengers and four who were in a silver Mini Cooper were taken to hospital as a precaution.
Detectives were investigating the circumstances of the crash that happened at the junction with Betty Haunt Lane at about 12.45pm.
Bus operator Southern Vectis said it is believed the double-decker ended up in the Fiat’s path after a crash moments earlier.
General manager Richard Tyldsley said: “Early indications suggest a car pulled out in front of a route 7 bus and our driver was unable to avoid it. The bus was forced into the path of another car.
“At this stage the full circumstances of the incident are unclear but sadly I understand one of the cars’ occupants has died.
“This is very distressing for all concerned and I would like to pass our sincere condolences to their family and friends.”
The operator would assist the police and conduct its own investigation, he added.
A spokeswoman for Isle of Wight NHS Trust said a “major incident” was declared just after 1.50pm, with four people being airlifted to mainland hospitals and 15 being taken to St Mary’s Hospital in Newport.
People were asked not to attend the emergency department unless “absolutely necessary”.
Isle of Wight Fire and Rescue Service group commander Justin Harden told the island’s County Press newspaper: “My thoughts are with the deceased’s family, on behalf of everybody here.
“It has been a significant incident, the like of which we have not seen for some time.”
Holidaymaker Alisha Smith, 23, said the double-decker hit a second car after colliding with a Mini that pulled into the road.
“We were driving down the road. A Mini pulled out from a side road,” she told the newspaper.
“The driver did his best to avoid it, but we hit and then bounced on to hit another car following in a different direction.
“The next thing I know, I was on the floor and got up to see if everyone was okay.
“A few were hurt and covered in blood, but no one severely injured at the top.”
Two air ambulances attended and casualties have also been taken to hospitals in Southampton and Brighton, Hampshire Police said.
The major incident was stood down shortly before 5pm, but the trust said the hospital remained in a “critical incident status” to ensure all patients were treated.
An Isle of Wight Council spokesman said: “The council understands public concern about what has happened at Forest Road and expresses its sympathies to all those who have been affected.
“Relevant Island agencies and the police are still investigating the causes of this incident and, until they have completed their work, it is inappropriate to comment further.
“In general terms, any decision by the council to implement road safety measures is something that would be only done following the advice and input of those relevant agencies and experts after a thorough investigation of the circumstances of what happened.
“The council hopes the public will understand this cannot be done immediately.”