The Marine Corps has released the names of four Marines killed at Camp Pendleton in San Diego County on Wednesday.

The deceased have been identified as:

Sgt. Miguel Ortiz, 27, of Vista

Staff Sgt. Mathew R. Marsh, 28, of Long Beach

Gunnery Sgt. Gregory J. Mullins, 31, of Bayou L’Ourse, La.

Staff Sgt. Eric W. Summers, 32, of Poplar Bluff, Mo.

The Marines were members of the Explosive Ordnance Disposal (EOD) community. Camp Pendleton released the following information about the fallen Marines:

One of the Marines had direct ties to San Diego County. Sgt. Miguel Ortiz of Vista was an EOD technician stationed at Camp Pendleton. Ortiz joined the Marine Corps in March 2006 and was promoted to sergeant in Nov. 2009.

During his career, Ortiz earned several awards, including the Navy and Marine Corps Achievement Medal, Combat Action Ribbon, two Marine Corps Good Conduct Medals, National Defense Service Medal, Afghanistan Campaign Medal, Iraq Campaign Medal, Global War on Terrorism Service Medal, Korean Defense Service Medal and NATO Medal-ISAF Afghanistan. Ortiz deployed to Iraq in 2007, the Western Pacific in 2008 and, most recently, Afghanistan in 2012.

Staff Sgt. Mathew Marsh worked with Ortiz as an EOD technician. Marsh joined the Marine Corps in 2003, became a staff sergeant in 2009 and has also earned many awards during his military career. He has deployed twice to both Iraq and Afghanistan.

Gunnery Sgt. Gregory Mullins was an EOD Staff Non-commissioned Officer-in-Charge. He joined the Marines in 2003 and was promoted to his current rank this year. He has received multiple awards, including during his two tours in Afghanistan.

Staff Sgt. Eric W. Summers was an EOD technician assigned to the 3rd Marine Aircraft Wing. During his 13 years in the Marine Corps, he was highly decorated and deployed to the Middle East five times.

Camp Pendleton's Commanding General, Brig. Gen. John W. Bullard, released this statement Thursday night:

Today, our thoughts and prayers are with the families of the Marines we lost yesterday. Explosive Ordnance Disposal is a small and tight-knit community, not just in the Marine Corps, but in the entire US military. Our focus now is on ensuring these families receive the help and support they need.

The Marines were killed in an explosion in the Zulu impact area, a live-fire artillery range in the middle of Camp Pendleton. According to base officials, they were trying to dispose of unexploded ordnance.

Base officials said there was no live firing on the Zulu range at the time of the accident.

The investigation is ongoing, and details about the accident are still limited.

The Marine Corps planned to publicly release the names of those killed 24 hours after their families had been notified.

Three others-- two Marines and a Navy Corpsman-- were nearby when the blast happened. They were treated at the scene, according to officials.