It’s an early morning training mission for Camp Pendleton military personnel.

A private contractor has them loaded onto a bus heading to an offsite training location to take part in controversial trauma training.

Once there, they'll be trained on lifesaving techniques using living pigs and goats who are cut, shot and have limbs severed to simulate battlefield conditions. It's training to save the lives of their comrades but critics say it's cruel, ineffective and inefficient.

“It doesn’t really benefit as much as it sounds,” one of the Marines told NBC 7 Investigates.

Two Marines shared their experience and first-hand knowledge of the training program. Both have been in the Corps for over 10 years. Their names and faces have been concealed to protect them.

They said the training is done with some secrecy. According to the Marines who spoke to NBC 7 Investigates, Navy Corpsmen and Marine special forces are told to wear civilian clothes for the training and "before they get on the bus, they take everyone's cell phone away.”

"They don’t want anyone taking pictures or video and putting it on YouTube or social media," one Marine said.

Both said they believe the U.S. Marine Corps and the U.S. Navy are under pressure to stop the program which is funded by U.S. Department of Defense contracts.

The Marines said the men and women being trained are at times conflicted by what happens during the live animal trauma training.

"We are compassionate people, trying to save lives but you are part of something that inherently inflicting pain and suffering on an animal,” one of the Marine’s said.

According to published reports and government documents, the U.S. Air Force and U.S. Army are reducing their use of goats and pigs to train their personnel to prepare for responding to medical emergencies on the battlefield and are instead opting for simulators. Some bases have stopped this practice completely. The Army has ended it for non-medical personnel and advanced career training courses.

One type of simulator is called a “cut suit,” made locally by Strategic Operations. They are manikins with special effects and are sometimes worn by humans to simulate the realistic responses that come with responding to traumatic injuries.

You can see video from Strategic Operations of the "cut suit."

WARNING: This video is graphic.

The People for Ethical Treatment of Animals (PETA) and other animal rights groups argue live animal trauma training is cruel. The groups also say they are flawed because of the anatomical differences between humans and animals. For example, they say goats and pigs have smaller torsos than humans.

One animal advocacy group, Physicians Committee for Responsible Medicine provided NBC 7 Investigates with a study from the University of Minnesota. The study was done on behalf of the DoD and according to the study, “simulators are cheaper than animal use,” because, according to the study, live animals are cheaper initially but after approximately 300 uses the simulators becomes more cost effective to use in training.

Click here to read the study.

According to a statement sent to NBC 7 Investigates, the Department of Defense's goal is to reduce the use of live animals in medical training. However, according to the statement, the department is continuing to assess its training methods and cites training studies that suggest using a combination of simulation and live tissue training is appropriate.

The live animal trauma training the Marines described were part of a contract awarded to Simmec Training Solutions. California State records show the corporation’s Chief Executive Officer is Merri Tyrre. According to DoD records the company is based in Virginia Beach, Virginia and has an office location in Oceanside.

Since 2008, the company has been awarded more than $6 million in DoD contracts nationwide, according to the website usaspending.gov. According to a December 2015 contract, the company was awarded $1.2 million to train personnel at Camp Pendleton.

Click here to see more details on the contracts.

Simmec’s Tyrre declined to comment for the story.

PETA has been actively advocating for the military to eliminate animals from the training program for years.

In 2016, 71 members of Congress sent a letter to then Secretary of Defense Ashton Carter urging the secretary to reduce the use of live animals in combat medical training. It was a bipartisan effort and one of the signers of the letter, Congresswomen Jackie Speier (D-San Franciso/San Mateo Counties) told NBC 7 Investigates she remains a lead on this effort but the position on the new administration on this issue is unknown and no immediate action is expected.

Read the full statement from the DoD below:

“As stated in the National Defense Authorization Act for FY2013, the Department's goal is to reduce the use of live animals in medical training and to increase the use of validated simulation training platforms. However, the combat casualty care training studies suggest that the DoD's current approach to combining both simulation and live tissue training to prepare corpsmen to care for those injured in combat is appropriate given the fact that management of complex trauma has not been successfully simulated with current technology. DoD will continue to assess its training methods as new data become available and as innovative technologies present opportunities for enhanced realistic training that improves care provided to service members in a combat environment. Medical training courses prepare corpsmen to diagnose and successfully treat wounds they will encounter on the battlefield, consequently saving the lives of thousands of wounded Marines and Sailors.”