RIO VISTA (CBS SF) — Crews made progress early Tuesday on a wildfire that erupted in the grassland along the Delta near Rio Vista, authorities said.

On the Rio Vista Fire Facebook page, officials said the fire erupted around 1 a.m. near the intersection of Highways 12 and 160 in the grassland across the waterway from the Delta town.

Arriving crews reported there were “multiple fires with a rapid rate of spread.” A second alarm was called in and crews began making progress in containing the fire.

Mutual aid crews from Isleton, Montezuma, River Delta, Fairfield, Suisun City and Contra Costa County Fire were in the scene as were members of a pre-positioned Solano County strike team.

The region currently was under a red flag warning with gusty winds and low humidity elevating fire conditions. It was the second blaze to break out in Solano County over the last 24 hours.

On Monday, fire crews converged on a brush fire burning near State Route 12 and Walters Road in Suisun City that temporarily shut down the roadway in both directions. A sig-alert was issued at about 3 p.m. regarding a vegetation fire along State Route 12 between Walters and Scally Lane.

Suisun City brush fire that closed State Route 12 (CBS)

The fire reportedly reached three alarms and created a large plume of smoke that was visible from miles away. The Contra Costa County Fire Protection District said its helicopter had assisted in battling the fire and it had been extinguished as of 4:50 p.m.

Travis Air Force Base firefighters assisted in the battle to contain the fire. There was no immediate word of any injuries or structures damaged.

The CHP said eastbound and westbound lanes of Highway 12 had reopened as of 4:37 p.m.

The cause of the fire was not known.