We surveyed a national sample of United States physics faculty about the COVID-19 transition to online learning. Most faculty had 1–2 weeks to prepare and no experience with teaching online. They relied on department peers to discuss approaches and used lecture adaptations such as video conferencing rather than new curricular elements. Their responses were empathetic to the students' situation, and 90% believed they were average or above at implementing online instruction. Faculty's preference for local resources and existing methods suggests that in a crisis, strong network ties will dominate as information sources, with consequences for professional development and instructional change.