The incident took place at 4 pm in the Sharjah Industrial Area 3 last evening, Khaleej Times reported today.
The four - two Indians and two Pakistanis - have been admitted to the intensive care unit of Al Kuwaiti Hospital following the accident.
A traffic official said the pile-up occurred due to overspeeding and lack of sufficient gap between the cars.
The impact was so powerful that one of the cars veered off the road and crashed into an outlet selling auto spare parts before coming to a halt.
On June 9, an Indian expatriate had killed and four others were severely injured in a collision between two cars in Sharjah.