SEATTLE — Snohomish County authorities say a massive landslide in Washington state has killed two people, injured six others and destroyed at least six houses.

An estimated mile-long slide of dirt, trees, rocks and other debris hit just before 11 a.m. Saturday.

Snohomish County spokeswoman Shari Ireton says a 6-month-old infant was among those injured.

Authorities believe the slide was caused by ground water saturation from recent heavy rainfall.

The landslide has completely blocked State Route 530 near the town of Oso, about 55 miles north of Seattle.

Also blocked is the North Fork of the Stillaguamish River, which is expected to cause flooding in the area.

Sheriff’s spokeswoman Bronlea Mishler says two died after an estimated mile-long slide carried a house with people inside across a rural road north of Seattle.

Five people injured in the Snohomish County landslide have been brought to a nearby hospital for treatment, said spokeswoman Jennifer Egger of Cascade Valley Hospital in Arlington.

It’s unclear if the two killed are among those injured, or if any of those people were inside the house that was swept away.

Cascade Valley Hospital was expecting more injured people, but Egger said she didn’t know how many and couldn’t comment on the condition of those already at the hospital because they were still being evaluated.

The American Red Cross has set up at the hospital and is seeking donations of food, water, blankets and clothing, Egger said.

The Daily Herald reported that as of 1 p.m., officials were moving rescuers back from the scene, citing concerns of the North Fork Stillaguamish River rising because of the mudslide.

“Initial reports were that a house was stuck in the slide, and someone was calling for help inside,” Trooper Mark Francis said.

Search-and-rescue operations are underway by Snohomish County crews and the Washington State Patrol.

The Washington Department of Transportation says mud, trees and building materials are blocking both directions of State Route 530 near the town of Oso, about 55 miles north of Seattle.

Heavy rain over this past week likely contributed to the mudslide. Saturday’s weather was sunny and clear.

Spokesman Bart Treece of the Washington State Department of Transportation said he doesn’t know how long the two-lane rural road will be closed. Drivers are advised to find another way to get between Darrington and Arlington, he said.

“We’re standing by ready to help out where we can,” Treece said.