Quantico Marine Base Shooting Victims, Gunman Identified

March 24, 2013— -- A decorated machine gunner who served tours of duty in Iraq and Afghanistan was identified as the man who allegedly gunned down two of his colleagues at the Quantico Marine Base in Virginia before killing himself.

The Naval Criminal Investigative Service identified Sgt. Eusebio Lopez, 25, of Pacifica, Calif., as the shooter. Lopez appeared to have died from a self-inflicted gunshot wound, Lt. Agustin Solivan told ABC News.

The two victims in the Thursday night shooting were identified as Lance Cpl. Sara Castromata, 19, of Oakley, Calif., a warehouse clerk, and Cpl. Jacob Wooley, 23, of Guntown, Miss., a field radio operator, according to a news release from the Marine Corps.

The shooting occurred Thursday night at Taylor Hall, a barracks at the Officer Candidates School, where all three Marines worked as training personnel, said Col. David W. Maxwell, base commander at Quantico.

A 911 call was received by the Provost Marshal's office about 10:30 p.m. William County Police and military officials responded and were on the scene within five minutes, but did not report hearing any shots fired, Maxwell said.

Base residents were notified to keep their doors locked as authorities assessed the situation.

All three Marines were pronounced dead at the scene. The motive is under investigation.

"We send our prayers and condolences to the families, fellow Marines and friends of the Marines who were lost in this tragic incident," Maxwell said. "Our priority is to take care of and support all of those who are affected by this loss."

Lopez' 81-year-old great-grandfather issued a statement to ABC News station KGO-TV expressing disbelief.

"[They] told us they were investigating more, and they'd let us know," he said of his great-grandson. "He wasn't the type to do stuff like that."

ABC News' Luis Martinez and Anthony Castellano contributed to this report.