(CNN) -- Police believe a Louisiana man abducted his two young sons early Wednesday after breaking into the Florida home of the children's grandmother and tying her up.
The boys had been removed from the care of Joshua Michael Hakken and his wife, Sharyn Patricia Hakken, last year, and on Tuesday the couple's parental rights were terminated in Louisiana, investigators say.
Hakken, described as an anti-government protester, is believed to be armed, according to the Hillsborough County Sheriff's Office in Tampa. Investigators believe his wife is with him.
The sheriff's office told CNN there have been ongoing issues with Hakken since he attended an anti-government rally somewhere in Louisiana in June of last year. He was arrested at the rally on multiple drug charges, officials said.
Louisiana authorities have told Florida investigators that the children were initially placed in temporary foster care after being taken away from the Hakkens. Sometime later, investigators allege, the couple went to the foster care center, armed, and tried unsuccessfully to enter it.
At some point over the past few months, the children were sent to Tampa to live with their grandmother, Patricia Hauser, the mother of Sharyn Hakken.
"Somehow they found out where the kids were and an Amber Alert is being issued now," said Detective Larry McKinnon of the Hillsborough County Sheriff's Office.
Sheriff's investigators say Hakken entered Hauser's home at 6:30 a.m. Wednesday. She has told police that he tied her up and fled with the children in her silver 2009 Toyota Camry. That vehicle was found later in the day just a couple of blocks away from the home. The sheriff's office said the children now could be in a black 2006 GMC pickup registered to Hakken.
Authorities said the abducted children are Chase Hakken, 2, and Cole Hakken, 4. Both have brown hair and brown eyes and were last seen wearing pajamas.
"We suspect that the wife is with him. He has a history of being armed," McKinnon said.
Investigators have brought in the FBI to help them track the family, who could have left the state of Florida by Wednesday afternoon.