A brush fire broke out in San Ysidro Monday near the Dairy Mart Road exit on Interstate 5.
San Diego Fire-Rescue Department responded when the fire broke out just after 5 a.m. There were no homes threatened.
Fire officials believe the fire was sparked along the northbound lanes of I-5 and traveled to the southbound side through a storm drain.
"There was about a quarter acre of heavy brush involved with some pretty high flame lengths," said SDFD spokesperson John Fischer. "The fire spread rapidly to about a half acre."
A nearby water hydrant at a self-storage facility was shut down so water trucks were brought in to help fight the fire.
Approximately 35 firefighters were called to help out and the spread was stopped at a little more than half of an acre.
Fischer said challenges include "the very, very thick brush along the freeway and the river bottom."
The southbound lanes of I-5 were reopened at 8:10 a.m. following a SigAlert, the California Highway Patrol said.
NBC 7 Meteorologist Jodi Kodesh said firefighters were working in good conditions - high humidity and calm winds.
"I think they're going to be able to get a hand on that very quickly," Kodesh said.
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