GILROY, Calif. -- The Summit Fire was declared 100 percent contained at about 6 p.m. Tuesday by fire officials, according to a Cal Fire spokesman.

Cal Fire spokesman Guy Martin said the total acres burned by the blaze remained unchanged from Tuesday morning at 4,270. Officials expect to have the fire under control by the end of the week.

"Estimated control date is May 30 at 6 p.m.," Martin said.

Five additional firefighters were reported injured as a result of poison oak exposure, bringing the total number of injured firefighters to 12. All of the injuries have been minor.

Currently there are still more than 2,600 firefighters involved in fighting the fire but the number is expected shrink since the fire has been contained.

"They are starting to bring those down," Martin said.

The cause of the fire remains under investigation, although fire officials were able to pinpoint that the blaze began in an area where Summit Road becomes Loma Prieta Avenue at the Santa Clara-Santa Cruz counties border.

The fire was 85 percent contained by daybreak and had cost $11.2 million to fight.

Mother Nature also continued to aid firefighters on Tuesday as cool temperatures and light winds were forecasted in the fire zone.

The fire came to a standstill over the Memorial Day weekend after cool, moist weather allowed firefighters to gain a strong handle on the blaze.

Officials opened several roads into the area Monday afternoon after inspectors found they were safe, said David Shew, a battalion chief with the California Department of Forestry and Fire Prevention.

Hundreds of other evacuees will be allowed back in phases over three days as inspectors clear one area at a time, according to the department.

Inspectors are looking for hazards along roads such as fallen trees or live flames, and making sure homes that were partially burnt were still safe to enter. The ground also could be hot with smoldering coals or tree roots that are still burning.