(AP) -- The U.S. Navy says a sailor who was shot in the attack on a military facility in Chattanooga has died, raising the death toll to five people.

By:Joe Raedle/Getty Images News

The death occurred two days after a gunman killed four Marines during a shooting rampage on two military facilities.

Authorities say Kuwait-born Muhammad Youssef Abdulazeez, 24, unleashed a barrage of fire at a recruiting center in Chattanooga, then drove several miles away to a Navy and Marine reserve center, where he shot and killed the Marines, and wounded the sailor who died. Abdulazeez was shot to death by police.

The Navy statement did not give the sailor's name. He was identified by family as Navy Petty Officer 2nd Class Randall Smith, a reservist serving on active duty in Chattanooga.

WASHINGTON (AP) — The deadly shootings at military sites in Tennessee illustrate the threat that FBI officials have warned about: violence directed against a vulnerable government target by a lone gunman with apparent terrorist aspirations.

The FBI has not detailed a motive, but Thursday's attacks that killed four Marines and one sailor are under investigation as a potential act of terrorism.

Authorities are combing through the gunman's past to look for travel, contacts and online writings.

The federal government has raised alarms about the online spread of terrorist propaganda, including repeated exhortations by the Islamic State group and others for sympathizers to target police officers and military installations.

Here is a look at other recent attacks on military facilities in the U.S.:

— June 17, 2015: Guards shot and killed an armed man after he crashed his SUV and emerged holding a rifle while apparently trying to break into the Little Rock Air Force Base in Arkansas.

— Jan. 6, 2015: At Fort Bliss, Texas, an Army veteran and former clerk at the veterans' clinic there shot and killed a psychologist, then committed suicide.

— Nov. 13, 2014: Two Navy civilian police officers were wounded while confronting a knife-wielding man at the submarine base in Groton, Connecticut. The suspect was taken into custody.

— April 2, 2014: At Fort Hood, Texas, three soldiers died and 16 others were wounded in a shooting rampage by another soldier, Army Spc. Ivan A. Lopez, who then killed himself.

— March 24, 2014: A civilian truck driver, Jeffrey Tyrone Savage, took a gun from a petty officer on watch aboard a destroyer at Naval Station Norfolk in Virginia, and killed a sailor before being shot by Navy security forces.

— Sept. 16, 2013: Aaron Alexis, a mentally disturbed civilian contractor, shot 12 people to death at the Washington Navy Yard before he was killed in a police shootout.

— Nov. 5, 2009: Fort Hood Army Base, Texas: Army Maj. Nidal Malik Nadal Hasan, 39, was convicted in August 2013 for killing 13 people and wounding more than 30.

— June 1, 2009: Private William Long was killed and Private Quinton Ezeagwula was wounded when Abdulhakim Muhammad opened fire on the soldiers as they entered an Army-Navy recruiting station in Little Rock, Arkansas.