HOUSTON -- Nearly 700 pounds of marijuana were taken off the street Thursday after a traffic stop in southeast Houston turned into a major drug bust, authorities told KPRC Local 2.

The bust happened at about 8 p.m. Wednesday after a deputy with the Harris County Precinct 2 Constable's Office pulled over the driver of an air conditioning repair truck and noticed he was acting suspiciously nervous.

"The driver was real nervous the whole time. My understanding is that when he was out of the vehicle, he kept looking back over his shoulder towards those crates," Precinct 2 Detective Rick Holloman said. "When the officer asked about the air conditioners, he didn't acknowledge there were crates even in the back of the truck … claims he didn't work for an air conditioning company. He didn't know how the crates got to the back of the truck."

The deputy called in a Pasadena Police Department K-9 unit, which found nearly 683 pounds of marijuana inside two air conditioning crates.

Officials with the Precinct 2 Constable's Office estimated the value of the marijuana to be nearly $1 million. They said it is the largest drug bust the department has ever made.

The driver was taken into custody. Authorities have not said what charges he could face.