CNN  — 

Just two days after a US sailor shot two civilians and injured another at a Pearl Harbor Naval shipyard in Hawaii, another gunman opened fire inside Naval Air Station Pensacola on Friday, killing at least three people, and himself, and injuring several others.

Since 1993, US military installments have had more than 20 shootings. Here are some of the deadliest.

December 6, 2019: Pensacola Naval Air Station (Florida)

Details are still unfolding, but the Navy has confirmed the suspected shooter is dead. At least three people were killed and several others injured.

December 4, 2019: Joint Base Pearl Harbor-Hickam (Hawaii)

Active-duty US sailor Gabriel Romero killed two civilian workers and injured another before killing himself, officials said. Investigators have yet to identify a motive, but they say he chose his victims randomly.

April 2, 2014: Fort Hood (Texas)

Army soldier Ivan Lopez killed three people and injured 16 others before fatally shooting himself in the head. A US official later said Lopez had previously reported being taunted and picked on by soldiers in his unit.

September 16, 2013: Washington Navy Yard (D.C.)

Twelve Navy Yard workers were killed and eight others injured when military contractor Aaron Alexis went on a shooting rampage. Alexis was killed after an encounter with security officials.

November 5, 2009: Fort Hood (Texas)

In what is considered the biggest mass shooting at a US military base in history, Major Nidal Malik Hasan, an Army psychiatrist, opened fire inside the base’s processing center, killing 13 people and an unborn child and wounding 32 others. A wounded civilian officer managed to shoot Hasan, who was taken into police custody. Hasan was later sentenced to death and is currently on military death row at Fort Leavenworth in Kansas.

Correction: This story has been updated to correct the number of people killed by the shooter at the Naval Air Station in Pensacola.