SAN BERNARDINO: Investigators believe the female shooter in California, Tashfeen Malik, pledged allegiance to Islamic State group leader Abu Bakr al-Baghdadi on Facebook, US media reported on Friday, as the probe into the deadly attack intensified. The report comes two days after the carnage at an office year-end party in San Bernardino that left 14 people dead and 21 others wounded — the deadliest mass shooting in the United States since the Newtown school massacre in 2012.

While authorities have publicly cautioned it is too soon to call Wednesday’s carnage a terror attack, reports suggested Syed Farook, a 28-year-old US-born Muslim, and his 27-year-old Pakistani wife Malik may have been radicalised. Reports suggested the couple may have been motivated by the IS group, which declared the creation of an Islamic “caliphate” in Iraq and Syria after seizing large swathes of territory there — but not specifically directed to act.