A search is underway for a Massachusetts man suspected of killing his wife who should be considered "armed and dangerous," police said Tuesday.

Aaron Pennington, 33, is a suspect in the homicide of his wife, 30-year-old Breanne Pennington, who was found dead at their home in Gardner on Sunday, Massachusetts State Police said.

His car -- a white BMW 320 -- was found by a hunter in a wooded area of Gardner on Monday evening following a police alert for the vehicle, authorities said. A search involving multiple police agencies, including canine and aviation units, is currently underway in the area for the suspect.

"We're operating under the assumption that Mr. Pennington is still alive and on the run," Gardner Police Chief Eric McAvene Jr. told reporters during a press briefing on Tuesday.

First responders went to the Penningtons' home Sunday morning after their four children went to a neighbor's home "scared because they could not find their father and their mother was in her bedroom crying," and the neighbor called 911, according to a criminal complaint issued against Aaron Pennington by state police.

Breanne Pennington was found in a bed in an upstairs bedroom dead from an apparent gunshot wound to the face, according to the complaint. Responding Gardner police officers conducted a sweep and found no other individuals or any visible weapons inside the home, the complaint stated.

Investigators learned Breanne Pennington was planning to move with the children to Texas "to be away from Aaron Pennington," who suffered from mental health issues, according to the complaint.

"Breanne Pennington was known to have a firearm at the residence for her protection," though neither she nor Aaron Pennington possessed a license to carry firearms in Massachusetts, according to the complaint.

The complaint was issued against Aaron Pennington for unlawful possession of a firearm.

The area where the search is underway is a heavily wooded campground used by the Boy Scouts and churches, McAvene said. The grid search is large, he said.

Worcester County District Attorney Joseph Early Jr. urged anyone in the area to check surveillance footage, including trail cameras, amid the search.

Aaron Pennington served on active duty in the U.S. Air Force from 2015 to 2022, reaching the rank of senior airman, according to an Air Force spokesperson. He transferred to the reserves in mid-2022 before separating from the service on Feb. 17, the spokesperson said.

Early Jr. said police are looking to determine what kind of survivorship training the suspect may have had.

Authorities advised anyone who sees him to not approach and call 911 immediately.

"We are assuming that the man is armed with a handgun," Early said.

Aaron Pennington was described by police as being white, 6'2" tall, approximately 175 pounds with blond hair and blue eyes.

Anyone with information on his whereabouts is asked to contact the Massachusetts State Police at 508-829-8236 or the Gardner Police Department at 978-632-5600.