SAN JOSE (CBS SF/BCN) — A vegetation fire that erupted late Monday morning on a grassy hillside near San Jose’s Coyote Creek was contained by afternoon, according to authorities.

The blaze was reported at about 11:15 a.m. in the area of Silicon Valley Boulevard and Basking Ridge Avenue. Cal Fire tweeted early on that at least one structure was threatened by the fire.

It was being fueled by tinder-dry brush along a hillside that has been turned brown by months of drought conditions.

In less than an hour, the blaze — being referred to by authorities as the Silicon Fire — had grown from 2 acres to 20 acres, according to Cal Fire.

SJ brush fire near Coyote Creek (CBS)

“CAL FIRE Attack is currently 20 acres, still wind driven with a flanking fire,” the agency tweeted. “Units are still making access to the fire. CAL FIRE Air Tankers and Copter in bound.”

Fire officials said there have been no evacuations orders or warnings issued to residents living near the blaze.

As of about 12:45 p.m., San Jose Fire officials said the fire was at 80% containment.

Both Cal Fire SCU and San Jose Fire confirmed that the forward progress of the fire had been stopped at about 30 acres. Cal Fire air support resources have been released.

Spokesperson with the San Jose Fire Department Erica Ray said while there is no official cause yet, first responders noted they saw power lines arcing at the site which may have started the blaze.

KPIX 5 reporter Len Ramirez said that PG&E crews were focusing on mylar balloons stuck in transmission lines near the fire’s location. Neighbors said they saw an electrical explosion in the area as well.

“There was this huge boom and there was a bright flash of light that happened with it,” said Beth Ellis, who lives near where the fire started.

She said the fire was out of control in seconds.

“Because its hot and dry, the wind is blowing. I walked out and the flames were — Whoosh! — down the hill,” Ellis described.

The neighborhood was not evacuated, but nervous neighbors kept a close watch on the firefight. Some made plans just in case.

“Just pack up and go. I don’t know where we’d go, but get out of here,” said area resident Karen Astrachan.

“We’re in a drought. Everything’s dry. It’s a wake up call,” said neighbor John Leipelt.

Once the fire was brought under control, investigators and PG&E crews focused their attention on a high-powered transmission tower.

Two gold colored metallic balloons were still stuck on the lines Monday afternoon.

On its website, PG&E urges customers to secure metallic balloons, which can cause energized lines to spark and cause power outages.

“When it sparks, it’s big. And the boom…I can’t even explain how loud the boom was,” Ellis said.

The San Jose Fire Department says the official cause is still under investigation.

The fire was completely contained as of 2:35 p.m. with an initial estimate of 35 acres, according to officials. Fire crews remain on the scene mopping up and checking for hotspots.

Len Ramirez contributed to this story.