A Michigan family mysteriously vanished from their home over the weekend and has not been heard at all in a case that is baffling investigators.

"We're just very concerned," Fremont Police Department Chief Tim Rodwell told Fox News Digital. "The circumstances are strange."

Anthony and Suzette Cirigliano, both 51, and their two sons, Brandon, 19, and Noah, 15, disappeared Sunday and are believed to be in a silver 2005 Toyota Sienna minivan, authorities said.

CALIFORNIA MISSING FAMILY OF FOUR FOUND DEAD INCLUDING 8-MONTH-OLD: MERCED COUNTY OFFICIALS

Suzette Cirigliano and her husband anthony and a separate photo of their two sons

Anthony and Suzette Cirigliano, both 51, and their two sons, Brandon, 19, and Noah, 15, vanished Sunday from their Michigan home, and police are "very concerned." (Courtesy of the Fremont Police Department)

There has been no activity on the couple's credit cards or bank accounts, and Anthony's phone is turned off. Suzette's and the boys' phones were found in their home, officials said. A series of search warrants turned up no clues, Rodwell said.

Anthony works in finance, and Suzette had been caring for her elderly mother, who suffers from dementia. 

GEORGIA TODDLER QUINTON SIMON: MOM NOW 'MAIN FOCUS' OF INVESTIGATION, POLICE SEARCH FOR CHILD'S REMAINS

On Monday, the elderly mother was found wandering the streets of their Fremont neighborhood, which is about 45 miles north of Grand Rapids. 

The silver toyota that the Cirigliano family is believed to be driving in

The 2005 silver Toyota Sienna minivan that the Cirigliano family are believed to be driving. Anthony and Suzette Cirigliano, both 51, and their sons, Brandon, 19, and Noah, 15, vanished Sunday from their Michigan home. (Courtesy of the Fremont Police Department)

Police discovered that the Cirigliano family was not home and appeared to have left abruptly without making arrangements for the care of Suzette's mother, who is now with another relative. 

There were signs of trouble the night before when Anthony called 911 in distress just after midnight. "Anthony was complaining of some elaborate issue in regard to the Sept. 11 attack," Rodwell said. "He was displaying to my officers paranoia and some concerns in regard to the FBI and CIA."

Google map showing Fremont, Michigian

A Google map showing Fremont, Michigan, the city where the missing Cirigliano family lives. (Google maps)

Two officers visited the family home and spoke with Anthony for 45 minutes and with Suzette to make sure she was OK. However, police determined that no one was in imminent danger, Rodwell added.

"They seem like really good people who were taking care of their family," he said. "No one has had any problems with them." 

CLICK HERE TO GET THE FOX NEWS APP

Rodwell urges anyone with information to contact the Fremont Police Department at 231-924-2100.