ELKHART, Ind. — A northern Indiana woman has been arrested on two preliminary counts of murder after her two young children were abducted and found dead in a car belonging to a neighbor of hers who was shot to death, authorities said Tuesday.

The children found dead Monday afternoon are siblings Liliana Hernandez, 7, and Rene Pasztor, 6, of Fort Wayne, authorities said. An Amber Alert had been issued for the children earlier Monday, saying they were “believed to be in extreme danger.”

Police arrested Amber Pasztor, 29, on two preliminary murder counts after the children’s bodies were found in Elkhart, about 70 miles northwest of Fort Wayne. An autopsy Tuesday identified them as her children and determined they died of asphyxiation, Elkhart police Sgt. Chris Snyder said.

Elkhart County Prosecutor Curtis Hill said at a news conference Tuesday afternoon that he expected to formally charge Pasztor in the deaths of the children later this week.

“It’s a senseless tragedy,” Hill said.

The children are believed to have died in Elkhart County following their abductions in Fort Wayne, Hill said.

Authorities declined to say who the children were living with when they were abducted or why they were taken, and Allen County Prosecutor Karen Richards, whose jurisdiction includes Fort Wayne, said police have no indication of a motive in the case.

The children were found in a car belonging to Frank Macomber, 65, a neighbor of Pasztor, who did not have custody of her children, Richards said at the news conference.

Macomber probably died before the children were abducted, Richards said.

“We do believe there is some connection between Mr. Macomber and the woman who is being held in Elkhart County,” Richards said, referring to Pasztor, who she said lived near Macomber.

No one has been charged in connection with Macomber’s death, which has been ruled a homicide, the prosecutors said. All three deaths remain under investigation, they said.

Pasztor was being held in the Elkhart County Jail. It wasn’t immediately clear whether she had an attorney who could comment on her behalf.

“Miss Pasztor has been somewhat cooperative,” Hill said. Asked if she told investigators where they could find Macomber’s body, the prosecutor said only, “She gave information that was helpful to the investigation.”

Earlier, Snyder said investigators were working Tuesday “to put the pieces together” and determine what happened between the time the two youngsters were abducted in Fort Wayne and when their bodies were found.

Snyder said Pasztor parked outside the city’s police department Monday evening and began speaking to an officer who was leaving after completing his shift.

“She pulled up to him and explained to him that she was part of the Amber Alert and the two kids were in the back seat,” Snyder said, adding that the officer then saw the bodies of two children in the car.

Snyder said Pasztor was initially cooperative following her arrest before “she became pretty emotional. And that’s kind of where our detectives left it last night.”

Capt. Steve Stone of the Allen County Sheriff’s Department said officers were searching for Macomber, who authorities believe was with Pasztor at some point Monday, when they found his body early Tuesday in a wooded area near his home.