For four days, Maryland police had been searching for a former Baltimore County police officer and a female accomplice who they said had kidnapped the officer’s young daughters and gone on to commit several other crimes, including carjacking and robbery.
On Thursday afternoon, Pennsylvania state troopers attempted to stop a gray Ford Edge near the Maryland border that matched one in which the suspects had been traveling, Elena Russo, a spokeswoman for the Maryland State Police, said at a news conference on Thursday night.
The vehicle veered off the highway and struck a culvert in Smithsburg, Md. A crisis-negotiation team from the Maryland State Police tried to talk to those inside the vehicle, but received no response, she said. A “thick layer of smoke” in the vehicle obscured what was happening inside, Ms. Russo said.
Inside the vehicle, the police found two adults and two children who had all been shot in what the police described as an “apparent murder-suicide.” Three of them were dead. One of the children was taken to a hospital and was later pronounced dead, Ms. Russo said.
The adults were identified as Robert Vicosa, 41, of Baltimore, and Tia Bynum, 35, of Baltimore. The names of the children were not released by the police on Thursday night, but they are believed to Mr. Vicosa’s children, who were 6 and 7.
Maryland State Police said in a statement on Thursday night that investigators had found an assault rifle and other firearms in the vehicle.
Gov. Larry Hogan of Maryland said in a Twitter post on Thursday night, “We are grieving tonight over the unfathomable loss of two innocent children in what is clearly a horrific tragedy and heinous crime,” he said.
The spate of crimes began on Monday, the authorities said, when Mr. Vicosa, a former Baltimore County police officer, held a woman captive at gunpoint and fled with his two children, according to the York Area Regional Police Department. The Baltimore Sun identified the woman as Mr. Vicosa’s estranged wife and the mother of the two children.
On Wednesday, Mr. Vicosa and Ms. Bynum, a suspended Baltimore County police sergeant, were believed to have forced a man to drive them to several locations in the Baltimore area before releasing him unharmed.
The Baltimore County Police Department said on Thursday that Mr. Vicosa’s daughters were present during a robbery.
At a news conference on Thursday morning, law enforcement officials pleaded with Mr. Vicosa and Ms. Bynum to safely return the two children.
Chief Melissa Hyatt of the Baltimore County Police Department asked Mr. Vicosa and Ms. Bynum to drop the children off at a public safety facility or a safe location where an adult could care for them.
“Their well being and safety is everyone’s priority,” Chief Hyatt said. “We know that you are tired. We want to work with you on a safe and peaceful resolution.”
At the news conference, Chief Hyatt added that the involvement of Ms. Bynum, who had been assigned to the department’s criminal investigations bureau, was complicating the search.
“I can certainly say that when we have a situation that involves police officers, or former law enforcement officers, our challenges are significant,” she said.
The Baltimore Sun reported that Mr. Vicosa had been fired three months ago. It was unclear on Thursday night why Ms. Bynum had been suspended.