Seventeen people died and nine others were severely hurt when a bus crashed into a road sign, which the driver had not seen due to makeshift sun shield, in Dubai on Thursday.

The Oman-registered bus — a Mwasalat vehicle transporting people between Dubai and Muscat — was travelling along Sheikh Mohamed bin Zayed Road, carrying 31 passengers, when it crashed into a signboard at Al Rashidiya exit at 5.40pm.

Initial investigations revealed that the Omani driver, in his fifties, did not pay attention and took a lane that is not designated for buses.

He failed to spot several warning signs, a road bump and a height restriction chain, which alerts drivers that their vehicles is over the permitted height.

Trying to avoid crashing into a maximum-height sign, the driver swerved to the right causing the board to cut through the roof of the left side of the bus.

During questioning, the driver, who sustained moderate injuries, said that he had not seen the warning signage because he had installed a small curtain on his windshield to protect his eyes from the sun.

Ongoing investigations have revealed that the impact of the accident indicates that the driver was exceeding the speed limit of 40kph on that road.

In an image released by Dubai Police, the roof of the left side of the bus appeared to have been severely damaged while the right side remained mostly still in tact.

Police initially said 15 passengers were killed on impact while five others, including the Omani bus driver, in his fifties, were taken to Rashid Hospital to be treated for injuries ranging from "moderate" to "severe".

An hour later, police said two more passengers, including a woman, died in hospital, increasing the death toll to 17.

Police said an investigation into the cause of the "unfortunate incident" is under way and thanked the "competent authorities involved" for their co-operation.

The Oman government-owned bus company issued a statement on Twitter, offering condolences to the families of those who died and announcing the suspension of their daily E05 services between Muscat and Dubai until further notice. It said the decision to suspend the service, which ran three times a day, was taken in co-ordination with Dubai's Road and Transport Authority.

The company said it was working with Dubai authorities to investigate the incident.

"[The] Mwasalat family expresses its deepest condolences to the families of the deceased and wishes a speedy recovery to the injured," the statement said.

"Mwasalat has paid great attention to the incident immediately on receipt of the news and has been in direct contact with the competent authorities in Dubai to look into the incident."

Dubai Police Chief Maj Gen Abdullah Al Marri said the crash was a "tragic incident that led to the death of innocent people."

Though the cause of the accident has not yet been made known, he called on motorists to always be vigilant while driving.

"Sometimes a simple error or negligence during driving leads to serious consequences, as happened this evening, and resulted in the deaths of 17 people of different nationalities," he said.