A collective of Muslim groups in the US have raised almost $30,000 over the last two days for the families of victims of the shooting spree at a social service centre that left 14 dead and 17 wounded in San Bernardino, California.

The Muslims United for San Bernardino initiative is seeking to raise at least $50,000 for immediate needs of the bereaved relatives, including funeral expenses.

"If we exceed the $50,000 goal, we can even assist the families with long-term expenses or possibly donate to the regional center where the shooting took place," the group said.

The project was launched on Friday by Faisal Qazi, the president of MiNDS, an award-winning charitable organisation based in southern California, and Tarek El-Messidi, a prominent Islamic "social entrepreneur".