A powerful 7.3 magnitude earthquake struck southern Alaska on Wednesday, triggering mass evacuations along the coastline.

The U.S. Geological Survey recorded the quake at 12:38 p.m. local time (4:30 p.m. ET), with the epicenter located in the Pacific Ocean near the Shumagin Islands, southeast of Sand Point and close to the Alaska Peninsula.

Alarms blared and cellphones buzzed as emergency notifications urged people from the Kennedy Entrance near Homer to Unimak Pass by Unalaska to head inland or to a higher elevation.

Homer’s mayor, Rachel Lord, described the situation: “We heard reports of bumper-to-bumper traffic early on, as people rushed to evacuate the spit.”