Updated

Authorities in several states on Thursday searched for two young boys believed to have been kidnapped by their father from their maternal grandparents' Florida home after their grandmother was tied up.

During a news conference, an FBI agent and a colonel with the Hillsborough County Sheriff's office said tips about 4-year-old Cole Hakken and 2-year-old Chase Hakken have poured in from several states.

Authorities say the boys' father, 35-year-old Joshua Michael Hakken, entered his mother-in-law's house north of Tampa, tied her up and fled with the children. They said the children could be in a black 2006 GMC pickup owned by their father.

"It's the manner in which the kids were taken that concerns law enforcement," FBI Special Agent Dave Couvertier said.

Officials say Hakken and the children's mother, 34-year-old Sharyn Patricia Hakken, are the prime suspects in the abduction. An earlier news release said "both suspects are anti-government and have attempted a previous abduction at gun point in Louisiana," but Couvertier said officials are focused on the kids and not the parents' political views.

"We're working on the safe return of the entire family, specifically the children," he said. "We don't anticipate or expect them hurting their children and hopefully we can put the family back together."

The Hillsborough Sheriff's office has issued an arrest warrant for Joshua Hakken; he faces two counts of kidnapping, two counts of child neglect, two counts of false imprisonment, one count of burglary with a battery and one count of grand theft auto.

Authorities said that Joshua Hakken lost custody of his sons last year after a drug possession arrest in Louisiana and that he later tried to take them from a foster home at gunpoint. Officials also said that the children had been living with their maternal grandparents since last year and that the Hakkens were informed Tuesday by a Louisiana court that they'd been stripped of their parental rights.

The Tennessee Bureau of Investigation on Thursday morning issued a statewide alert after the family's car was believed seen in southeast Tennessee.

They were traveling in a 2006 black GMC pickup truck, bearing Florida license number U95KT. The vehicle may have been spotted in Etowah about 8 p.m. Wednesday.

Hillsborough County Sheriff's Office Col. Donna Lusczynski said law enforcement in the Southeast and Southwest are working to get information about the kidnapping onto billboards.