Heavy fog and snow on a major highway in Virginia, eastern USA, caused a massive collision involving at least 63 vehicles, injuring about 36 people.

State police said that there were no reports of deaths, but that many of the injured were in serious condition, and about 35 people had been transferred to district hospitals.

Cars collided with each other, causing the front and rear of many vehicles to crash, and rescue workers had to climb to the roofs of cars to reach the stranded people.

Local authorities opened an investigation into the accident, and efforts to clear the highway continued for more than six hours after the accident.

Police said that the weather conditions were threatening snow and visibility was low at the time of the accumulation, and the accident occurred east of Richmond, the state capital.

The weekend before Christmas is one of the busiest travel times of the year in the United States.