Brandon Jividen, 37, Rebecca Adams, 22, and Adams' children, Michelle Hundley, 5, and Jaracca Hundley, 3, have been missing for more than a week. Courtesy of Seeking Alaska's Missing

A massive search for a family of four in Alaska is focusing on nearby woods and the behavior of one of the missing, a mother of two young children.

Brandon Jividen, 37, Rebecca Adams, 22, and Adams' children, Michelle Hundley, 5, and Jaracca Hundley, 3, have been missing since May 27, 2014, according to a Facebook group Seeking Alaska's Missing.

The Kenai Police Department, the FBI and other state organizations are launching a "large" search effort.

"The FBI is assisting in all sections. We have dog teams and helicopter teams assisting as well," said Lt. David Cook. "The FBI has made a lot of resources available and we are pouring all our resources into the search. This is our top priority."

Cook said Kenai PD received a call on May 31 from one of the family's neighbors about a backyard shed door that was ajar. Five days later, police received another call from the same neighbor who told investigators that the family hadn't been home in days.

"At this point it's not apparent where they have gone or where they might be," Cook said. "The investigation does not show that is foul play at this point, but we are very deep into the investigation of the missing persons."

Although Cook would not go into detail about specifics of the investigation, he said the primary search area is a wooded area near the family's home. The family car is still in the driveway, he noted.

Cook also said Adams' family told investigators that Rebecca Adams had been acting strangely in the days leading up to their disappearance.

"The family has expressed some concern with the behavior of their sister Rebecca and have some concerns within her relationship [to Brandon]," said Cook.

The police urged the public to stay alert and help them while the official investigation continues.