Obama: Chattanooga shooting a 'heartbreaking circumstance'

President Obama speaks out about the tragic shootings in Chattanooga, Tennessee where four Marines were killed when a gunman attacked two military sites.

02:01 - Source: CNN
Chattanooga shooting
obama chattanooga tennessee shootings tsr_00012005.jpg
Now playing
02:01
Obama: Chattanooga shooting a 'heartbreaking circumstance'
chattanooga shooter personal issues tuchman pkg ac _00022728.jpg
Now playing
02:14
Marines 'willingly ran back into the fight'
chattanooga shooting investigation update serfaty dnt lead_00000624.jpg
Now playing
01:55
Chattanooga shooter followed writings of al Qaeda cleric
chattanooga shooting mohammed abdulazeez friend interview griffin ac _00010621.jpg
Now playing
01:16
Sources: Shooter searched 'martyrdom' online
obama addresses white house flag at half mast wolf _00000124.jpg
Now playing
01:00
White House, U.S. Capitol flags lowered to half-mast
armed civilian stands guard georgia_00000407.jpg
Now playing
01:45
Armed man stands guard at recruitment center
chattanooga shooter personal issues tuchman pkg ac _00022728.jpg
Now playing
03:36
Family spokesman: Chattanooga shooter had depression
Mohammad Youssuf Abdulazeez is the suspected gunman in July 16, 2015 Chattanooga, Tennessee Naval Reserve shooting that left four Marines dead and the gunmen also killed.
Now playing
01:55
What did the shooter's writings reveal?
A police car blocks the entrances to the Tennessee Naval Reserve Center on Thursday July 16 in Chattanooga, Tennessee. Authorities say Mohammod Youssuf Abdulazeez, 24, opened fire first on a military recruiting station at a strip mall and then moved to an operational support center operated by the U.S. Navy seven miles away, where he killed four U.S. Marines.   The gunman was also killed.
Now playing
02:21
States increase security for military installations
timeline chattanooga shooting tuchman dnt ac _00020811.jpg
Now playing
03:37
How the Chattanooga shooting unfolded
video captures chattanooga shooting live intv tsr wolf_00002506.jpg
Now playing
01:47
Witness records gunfire during Chattanooga shooting
chattanooga shooting investigation blackwell dnt tsr _00000127.jpg
Now playing
02:29
FBI begins 'terrorism investigation' in Chattanooga
chattanooga gunman new details todd dnt tsr_00014423.jpg
Now playing
02:46
Investigators look for clues about Chattanooga gunman
wounded cop fred fletcher chattanooga shooting nr sot_00003718.jpg
Now playing
01:09
Chief: Wounded cop dragged 'from under the gunfire'
Mohammod Youssuf Abdulazeez's mugshot from 4/20/2015
Now playing
01:36
Chattanooga shooter's father was investigated by FBI
chattanooga shooting mayor andy berke newday intv camerota_00013303.jpg
Now playing
02:36
Mayor: We had no indication shooter was a threat
thomas j sullivan
Now playing
01:14
Marine killed in Chattanooga shooting identified
chattanooga shooting fbi press conference live ctn_00003512.jpg
Now playing
01:18
FBI: We are checking every lead
chattanooga shooting
Now playing
04:07
Muslim community condemns Chattanooga shooting
tennessee shooter friend high school don lemon cnn tonight_00015214.jpg
Now playing
04:52
Friend of shooter: 'It's a wave of disbelief and shock'
chattanooga suspected shooter mma coach sot ac _00004629.jpg
Now playing
01:24
MMA coach: He was an All-American kid
chattanooga mayor andy berke sot ac _00000517.jpg
Now playing
01:10
Chattanooga mayor: Our hearts are breaking
chattanooga tennessee shooting blackwell dnt erin_00000323.jpg
Now playing
02:09
What do we know about Mohammad Youssuf Abdulazeez?
chattanooga shooter mma fight video swecker intv erin _00001317.jpg
Now playing
02:16
Video: Chattanooga shooter participated in MMA fights
chattanooga shooter vehicle griffin live erin _00001618.jpg
Now playing
01:34
Vehicle used in Chattanooga shooting a rental
Mohammod Youssuf Abdulazeez
Now playing
02:23
Coach: Chattanooga shooter was 'humble' and 'smart'
07 tn shooting
Now playing
01:27
4 Marines killed in Chattanooga shooting attack
witness chattanooga shooting gina mule
Now playing
01:59
Witness: 'I was in shock at how many times he fired'