MIAMI-DADE COUNTY, Fla. -

A southwest Miami-Dade County couple has been arrested after a fully operation underground marijuana laboratory was discovered in a swimming pool behind their home late Monday night, police said.

Miami-Dade police narcotics detectives said they made the discovery inside the covered shell of a pool at 21964 SW 125th Ave. while acting on a tip.

Luis Ramirez-Gonzalez and Yamile Gongar were arrested on charges of trafficking marijuana and possession of a place to manufacture a controlled substance.

Detectives said the underground lab stretched the length of the backyard.

"What's interesting is the steps that they took to create or build this underground grow," Lt. Jose Gonzalez said.

Detectives seized about 70 pounds of marijuana.

"We were in shock because we didn't see any signs or anything," neighbor Yeny Devarona said. "We didn't hear any construction."

The couple lived at the residence with their two daughters, ages 8 and 17. Their children were placed in the care of relatives.