"But we have no direct evidence of ties to any specific wing of ISIS or anyone else" a law enforcement source tells PEOPLE
Credit: KNBC via AP

The California couple that carried out the deadly shooting in San Bernardino on Wednesday may not have had direct ties to ISIS, a law enforcement source tells PEOPLE.

While the terrorist group has claimed shooters Tashfeen Malik, 27, and her husband Syed Rizwan Farook, 28, were supporters of ISIS, no direct evidence of a link has been found by investigators in the early stages of their investigation.

“We already know this couple was radicalized,” the source says. “They were terrorists. We established that. But we have no direct evidence of ties to any specific wing of ISIS or anyone else.”

On Saturday, the militant group called the shooters “martyrs” for the group’s cause on al-Bayan Radio, as confirmed by SITE Intelligence Group, which monitors radical groups’ online movements, the Associated Press reports.

However, ISIS often claims responsibility for attacks after-the-fact whether or not they were actually involved, according the Wall Street Journal.

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“ISIS says this was a strike for the cause,” the source continues. “They gave their stamp of approval.”

It was widely reported on Friday that Malik had pledged her allegiance to ISIS on her Facebook page, although federal officials told the Associated Press that there was no evidence that anyone from ISIS had responded to her post or instructed her to carry out the massacre.

The source added that investigators have not at this time found a terror cell or any group to which the couple belonged. Adding: “That’s not to say we won’t find one. As of now, we have not placed them within a specific group.”

In a press conference on Friday, the FBI said it would officially be investigating the shooting that killed 14 and injured 21 as an act of terrorism.