There ‘had to be some degree of planning’: 2nd San Bernardino suspect named Tashfeen Malik
San Bernardino Police Chief Jarrod Burguan speaks to reporters early on Dec. 3, 2015. [KNBC-TV]

The two suspects in Wednesday's mass shooting at a San Bernardino social services facility were either married or engaged, Police Chief Jarrod Burguan said at a press conference early Thursday morning.

Burguan confirmed earlier reports identifying one suspect as 28-year-old Syed Rizwan Farook. The second suspect, who was either Farook's wife or girlfriend, was identified as 27-year-old Tashfeen Malik.

Both suspects were killed while exchanging fire with police on Wednesday evening, following a pursuit that led authorities to a home in nearby Redlands.

The suspects are connected to an attack that left 14 people dead and another 17 injured at the Inland Regional Center. Burguan confirmed that Farook -- who was born in the US and worked for San Bernardino County for five years -- left a holiday party taking place earlier in the facility after some sort of argument before returning to the building and carrying out the attack.

The chief also expressed confidence that Farook and Malik were the only two perpetrators, adding that there "had to be some degree of planning" beforehand.

"I don't think they ran home, got these types of tactical clothes and came back on a spur-of-the-motive thing," Burguan said.