Ultimately no one was injured, and Cal Fire said no structures were threatened by the blaze off Springwood Court and California Street.
The fire produced bright flames near Interstate 80 and thick, dark plumes of smoke.
"We actually came home on Highway 4 saw the smoke, we thought it was a long ways so then we found out well it's close to home maybe it's closer than it should be," said Jonathan Westbrook.
The fire was close to the Phillips 66 refinery as well.
"We actually run a machine shop that provides parts for the refinery so when we saw it was up here we thought we better come see bc if it's something that hits the refinery we could get a call," said Shelley Salinero.
"We thought okay let's go see how big is it," said Stephanie Westbrook.
The Westbrooks were one of several families who stopped to look and take pictures.
"I've never seen a fire this big in person," said Katie Risner.
The fire attracted the attention of several kids as well. Many of them gathered in a neighborhood cul-de-sac with a direct view of the refinery and aerial response.
Happening now - grass fire in Rodeo has moved beyond refinery. Dozens of people on this overpass watching pic.twitter.com/XYMsqvkBnz— Melanie Woodrow (@MelanieWoodrow) July 8, 2017
2 Vallejo Fire Crews Assisting With Multi Alarm Vegetation Fire In Rodeo-Hercules/ Cal Fire Fixed Wing Aircraft Providing Support pic.twitter.com/AMJ85TmQDE— Vallejo Firefighters (@VallejoFire) July 8, 2017