SAITAMA (Kyodo) -- A large sinkhole swallowed a truck Tuesday after appearing at an intersection near Tokyo, with fire authorities working through the day to rescue a trapped man believed to be the driver.

Police received an emergency call at around 9:50 a.m. after the sinkhole, about 10 meters in width and 6 meters in depth, opened up in the ground in Yashio, Saitama Prefecture.

The man was initially conscious and capable of talking, according to the fire authorities. Two male rescuers sustained minor injuries after sediment fell on them while they were using heavy machinery to try to reach the man.

According to prefectural government officials, the road collapse may have occurred due to a heavily corroded sewerage pipe that runs 10 meters underground.

Surrounding sediment is believed to have flowed into the pipe, creating a hollow space under the road. Unable to withstand the weight as vehicles passed, the road collapsed.

The local government suspect that the corrosion was caused by sulfuric acid, which is formed when hydrogen sulfide -- also known as sewer gas because it is often produced by the breakdown of waste material -- is exposed to air.

The volume of water flowing through to a treatment plant from the sewage pipe has decreased compared to levels observed prior to the collapse.

Some witnesses said the road sunk just before the truck passed, according to the police.