Agents of the U.S. Navy’s Naval Criminal Investigative Service (NCIS) on Thursday arrested 16 U.S. Marines at Marine Corps Base Camp Pendleton in California on charges ranging from human trafficking to the possession of illegal drugs.

Eight other Marines “were taken aside to be questioned on their involvement in alleged drug offenses related to today’s arrests,” said the Marines.

The home of the U.S. 1st Marine Division, Camp Pendleton is the major West Coast base of the Marine Corps and is one of the largest Marine Corps bases in the country.

All the arrested Marines belong to the 1st Marine Division, specifically the 1st Battalion, 5th Marines based at Camp San Mateo inside Camp Pendleton. None of the Marines arrested were assigned to enforcement duties along the U.S. border with Mexico as part of the Southwest Border Support mission.

The Marine Corps command emphasized the 1st Marine Division is committed to justice and the rule of law, and will continue to fully cooperate with NCIS on this case. It said any Marines found to be in connection with these alleged activities will be questioned and handled accordingly with respect to due process.

“The investigation is ongoing,” said division spokesman, 1st Lt. Cameron Edinburgh. “They were taken into custody by NCIS personnel.”

Charges against each of the Marines were pending and no information is yet available. Division officers said the arrests and investigation were triggered by “information gained from a previous human smuggling investigation.”

This human smuggling investigation refers to the arrests of two Marines (Lance Cpls. Byron Daniel Law II and David Javier Salazar-Quintero assigned 1/5 Marines) on July 3. Both men were stopped in the Boulevard/Jacumba area east of San Diego by U.S. Customs and Border Protection (CBP) agents.

US Marines
This representational photo reviewed by the U.S. military shows the United States Marine Corps emblem hanging on a wall at the Joint Detention Forces Headquarters at Guantanamo Bay U.S. Naval Base, Cuba, April 9, 2014. Getty Images/ MLADEN ANTONOV

These agents said they came across a black car driven by both Marines in an area along Interstate 8 known for smuggling. Law was driving while Salazar-Quintero was in the front passenger seat, according to a Marine account of the arrest. There were three Maxicans in the back seat.

The three men told the CBP agents “they are citizens of Mexico without any immigration documents that would allow them to enter or remain in the United States legally.”

Two of the Mexicans told investigators “they were going to pay $8,000 to be smuggled into the United States.” They intended to travel to New Jersey and Los Angeles. All five men were arrested.

“Law claimed that (Salazar-Quintero) was the individual responsible for organizing the event” and solicited Law’s involvement, hours earlier, “picking up an illegal alien” in return for $1,000, the complaint stated.

Law said the two Marines had picked up that individual in Law’s black BMW and dropped him off at a McDonald’s in Del Mar then returned to Camp Pendleton.

The following morning, Salazar-Quintero called Law “for another job” and both Marines returned to the border area. They picked up the three men before CBP agents pulled them over and arrested them.

CBP said Salazar-Quintero “admitted coming to Jacumba to pick up on four different occasions.

Both Marines pleaded not guilty at their July 17 arraignment in U.S. District Court in San Diego and were released on $10,000 bonds. Both are required to submit to drug testing, according to court records.

A motions hearing is scheduled for Aug. 5.

Capt. Christopher Harrison, Marine Corps spokesman, told CNN the corps is "aware of the charges facing Lance Cpl. Law and Lance Cpl. Salazar-Quintero."

"We continue to cooperate fully with the investigative efforts into this matter," he said.