OAKLAND (CBS SF) — Flames roared through a homeless encampment nestled under the Grand Ave. onramp to the MacArthur Maze early Tuesday, igniting vehicles and makeshift shacks and threatening the structural integrity of the vital roadway leading to the San Francisco-Oakland Bay Bridge.

Oakland firefighters responded to reports of the blaze near Wood St. and Grand Ave. around 3:43 a.m.

READ MORE: Former MMA Champ Cain Velasquez Arrested In San Jose Shooting

Arriving crews quickly called in for reinforcements after discovering several makeshift living structures ablaze with flames spreading to an RV and old bus. Propane tanks were also ignited.

READ MORE: Fourth Suspect Arrested In San Jose April 2021 Homicide

The flames roared near the concrete supports of the Grand Ave. onramp to the MacArthur Maze forcing Caltrans to shut it down over fears the heat may be compromising its structural integrity.

Firefighters also had to bring in extra equipment to provide a steady source of water and had to cut through a chain link fence to access the fire.

MORE NEWS: VIDEO: Suspects Ditch Car, Run From Police In San Francisco Noe Valley Chase

There were no reports of injuries. The fire was contained around 5 a.m.

Source: sanfrancisco.cbslocal.com.