Ferndale, California - The magnitude 6.4 earthquake that rattled Northern California early Tuesday resulted in at least two deaths from medical emergencies, according to authorities.

The quake was reported at 2:34 AM just offshore about 7 1/2 miles southwest of Ferndale, according to the US Geological Survey. No tsunami was expected, the Sheriff’s Office said on Twitter, but the agency advised residents to prepare for aftershocks.

The Humboldt County Sheriff’s Office said two individuals have died as a result of medical emergencies occurring during or just following the earthquake, and at least 11 people have sustained injuries.

There was one fatality in Rio Dell during the earthquake, Rio Dell Mayor Debra Garnes, said, but it is unclear if it was related to the tremors.

Emergency dispatchers also received two reports of injuries, including a broken bone and a head injury, with both patients expected to survive, said Samantha Karges, a public information officer with the Humboldt County Sheriff’s Office.

Additional reports of injuries are being verified, the Sheriff’s Office said.

There was extensive damage to roads and homes, Karges said. Most of the destruction is in Rio Dell, Fortuna, Ferndale and Scotia in the Eel River Valley. There was one confirmed structure fire in Rio Dell associated with the earthquake that has since been put out, said state Sen. Mike McGuire, a Democrat who represents Humboldt County.

According to PowerOutage.us, more than 14,000 people across Humboldt County were without power on Wednesday morning. Several gas leaks were reported, as well as damage to water lines, Karges said.

Exactly one year ago, the same area was hit by a magnitude 6.2 quake that shattered windows and caused other damage.

Since the 6.4 earthquake, there have been an estimated 80 aftershocks, including three registering 4.6, 4.0 and 3.9, said Cindy Pridmore, a geologist with the California Geological Survey.