Naval Criminal Investigative Service carried out a mass arrest of 16 Marines Thursday morning during a battalion formation aboard Camp Pendleton, California, according to Marine Corps officials.

The Marines were arrested for allegations related to “various illegal activities” from human smuggling to drugs, the Marine Corps said in a press release.

Maj. Kendra Motz, a Marine spokeswoman, told Marine Corps Times that the Marines questioned and arrested by NCIS ranged in rank from private first class to corporal and hailed from 1st Battalion, 5th Marines.

Another eight Marines were questioned about their involvement in unrelated drug offenses, according to the press release. The Corps said that none of the Marines questioned or detained Thursday have been supporting military operations at the U.S.-Mexico border.

“1st Marine Division is committed to justice and the rule of law, and we will continue to fully cooperate with NCIS on this matter,” the Marine Corps said in the release.

The mass arrests follow the July 3 arrest by Border Patrol agents of two Marines, Lance Cpl. Byron Darnell Law II and Lance Cpl. David Javier Salazar-Quintero, near the U.S.-Mexico border.

The two Marines are both riflemen assigned to 1st Battalion, 5th Marine Regiment, 1st Marine Division, at Camp Pendleton, California.

Both Marines face federal charges for allegedly smuggling three undocumented immigrants near the U.S.-Mexico border for financial gain, court documents detail.

The Marine Corps said in Thursday’s press release the 16 Thursday arrests were based off information learned during a previous investigation.

Marine officials with 1st Marine Division worked alongside NCIS during the arrests, the release said.

“Any Marines found to be in connection with these alleged activities will be questioned and handled accordingly with respect to due process,” the Corps said.