Homeland Security, Drug Enforcement Administration agents, hazmat crews and fire trucks descended on a residential home near downtown San Jose on Friday morning, causing a stir in the neighborhood and yielding at least one arrest.

The suspect wasn't immediately identified.

Raw video: San Jose Home Investigate Possible Meth Lab

Homeland Security spokeswoman Virginia Kice said her agency was conducting a search warrant as part of an "ongoing investigation." She said that "due to certain evidence inside the home, appropriately trained personnel" needed to handle that evidence.

While she wouldn't say specifically what the search was about, a San Jose firefighter who didn't give his name told NBC Bay Area the home at 330 North 20th Street near Julian Street was suspected of containing a meth lab, where 15 pounds of methamphetamine totaling $100,000 was recovered.

Two children younger than 10 lived at the home, the firefighter said.

Aerial images showed investigators in a backyard, strewn with debris and buckets containing undetermined substances. A huge fan was also seen sitting on the street.

Santa Clara County Deputy District Attorney Patrick Vanier said the drugs appear to have come from Mexico in liquid form. He said San Jose is a "transfer point" where meth is taken from a liquid state and processed into crystal meth.

The discovery of the meth lab "shows the trend of Mexican national drug cartels operating in Silicon Valley," Vanier said.

An NBC Bay Area photographer witnessed the emergency vehicles surrounding the home shortly before 9 a.m.

Kice said it wasn't unusual for Homeland Security to be involved in a joint DEA investigation.

"We don't just do immigration cases," Kice said, saying the agency also deals with investigations including child sex exploitation cases and narcotics busts, especially if the contraband crosses borders -- real or virtual.

Kice said all related documents in the case are under seal. She did state, however, that there is no threat to the public.

Meanwhile, Alameda County Sheriff's Sgt. J.D. Nelson said a drug task force uncovered a small meth lab on Berkeley on Friday morning in a home on Oregon Street.

NBC Bay Area's Lisa Fernandez, Alan Waples, Shelby Hansen contributed to this report.