In the wake of Wednesday's shooting rampage in San Bernardino, California, law enforcement officials are working to figure out what exactly happened before, during, and after husband and wife suspects Syed Farook, 28, and Tashfeen Malik, 27, killed 14 people and injured 21 at a social services center.
Here's the latest that we've learned.
The couple was clearly on a "mission," officials told reporters on Thursday morning and, while authorities insist that there is not a clear motive yet, Farook appears to have been radicalized. Authorities tell NBC News he was in touch with persons of interest in the Los Angeles area and abroad who have expressed Jihadist-oriented views or were persons of interest to American authorities.
They were heavily armed. The pair had 1,400 .223 caliber rounds and 200 9-mm rounds on their person or in their vehicle. There were also 12 pipe bombs, as well as nearly 5,000 additional rounds, in the Redlands home where they lived, according to police.
The carnage at Inland Regional Center could have been worse: A pipe bomb left where the shooting started was attached to a remote control car but did not detonate, seemingly indicating that they intended to trigger the bomb after law enforcement and emergency responders had reached the scene. Authorities tell NBC News the controller was similar to the one that was used in the Boston bombing attacks.
One of Farook's coworkers tipped off police. Law enforcement officers told reporters on Thursday that a coworker had reached out to police after Farook left the holiday party. After officials determined that Farook had rented a car that looked like the escape car, they converged on the couple's Redlands home where a shootout killed both suspects.
Here’s what we still don’t know.
What the motive was: Despite speculation, we don’t know the motive, potential underlying ideology or possible mental illness related to this shooting. The two individuals were both here legally: Farook was born in Illinois, a citizen by birth, and Malik entered on a fiancé visa; the couple had a six-month old child.
"At this stage we do not yet know why this terrible event occurred," President Obama said Thursday morning, announcing that the Federal Bureau of Investigation would take over the investigation. "It is possible that this was terrorist-related, but we don't know. It's also possible that this was was workplace-related."
Are there any accomplices? Authorities are searching for possible accomplices who may have helped the pair obtain weapons, ammunition, or the materials for the bombs
Whether it’s linked to a terror cell: Investigators have not ruled out whether the couple were working with a terror cell, or if they were acting independently. Farook traveled Pakistan in 2014 and Saudi Arabia earlier this year, and was speaking with individuals the FBI was monitoring, according to NBC News, but the ties are still tentative and speculative.
"Don't have all the facts yet," FBI Los Angeles Assistant Director in Charge David Bowdich told reporters at a press conference when asked about potential terror ties. "It would be irresponsible and premature of me to characterize this as terrorism."
Who purchased their long guns: Farook and Malik were armed with four weapons -- two handguns and two long guns -- which were all legally purchased; the two handguns were purchased legally by Farook, but it's unclear who purchased the long guns, police said.
How long they were planning this: Farook attended an office holiday party shortly before the shooting, but police say it's clear the shooting was planned in advance as gunfire began between 10-30 minutes later, which didn't leave time for Farook and Malik to return to their home, obtain weapons, put on the black tactical clothing and get back to his workplace in time. Still, how the couple were able to plan this -- undetected -- is unclear.
Were they planning anything else: The attackers were wearing masks in an apparent attempt to conceal their identities — and with the significant ammunition and additional bombs at home, it's unclear if the were planning anything else besides the shooting that occurred. The bombs found in the couple's home were similar to those found in al Qaeda's Inspire magazine, authorities told NBC News, but it's unclear whether the pair had ties to the terror group or obtained that information on their own.