Last week's mass shooting in San Bernardino, Calif., that killed 14 was reportedly planned up to a year in advance.

The suspected killers began practicing with guns and making financial preparations in 2014, according to NBC News.

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Syed Rizwan Farook and Tashfeen Malik began honing their firearms skills last year at a shooting range in Riverside, Calif., NBC said, citing two sources.

Counterterrorism officials said the pair began saving money for their daughter and Farook’s mother during the same period.

“[They wanted to] take care of both Grandma and the baby,” one official told NBC News, referencing the couple’s 6-month-old and Rafia Farook, 62.

“They had purposely thought through that problem,” they continued. "[Some transactions] would be consistent with them making preparations for grandma and the kid.”

“There were other indications of preparation,” the official added, not specifying further details.

Farook and Malik left their child with Rafia Farook at their home in Redlands, Calif., the morning of Dec. 2, according to NBC News.

They then opened fire inside the Inland Regional Center in San Bernardino, authorities say, killing 14 and wounding 21. Police killed the duo during a shootout in Redlands, Calif., later that day.

Reports emerged Tuesday that Syed Farook received a $28,500 bank deposit from WebBank.com two weeks before the massacre. At least three subsequent transfers of $5,000 apiece went to Rafia Farook before the attack.

The FBI is now investigating the incident for ties with terrorist organizations including the Islamic State in Iraq and Syria.