The fatal plunge of a woman and two children from the top of a Boston parking garage on Christmas Day is believed to have been suicide by the mother, authorities said Thursday.

Erin Pascal, 40, of West Roxbury, her 4-year-old daughter, Allison, and her 15-month-old son, Andrew, were found unresponsive on a sidewalk outside the Northeastern University garage and pronounced dead at the hospital.

Suffolk County District Attorney Rachael Rollins said their deaths were “likely” a double murder-suicide, the Boston Herald reported.

“This entire family, in a matter of minutes, is gone beside the father,” Rollins told reporters during a press conference. “This is an extremely sad day as we begin to put together the pieces of a tragedy that took place yesterday on Christmas.” Rollins said the incident occurred between 1:25 p.m. and 1:35 p.m. on Wednesday.

Sources told WCVB-TV that Pascal’s husband called police when she left their Boston-area home with the children after an argument. He reportedly believed that she might be suicidal—and Rollins said all indications are that he was right.

“Our investigation is showing the two children fell first, and then the parent after,” Rollins told WBUR-TV.

“It was awful,” she said. “There were belongings from the children and the mother strewn upon the street. The impact of the fall was visible from the street.”

Rollins said police found a vehicle, which was linked to the victims, parked across two spaces on the roof of the garage. Video showed investigators combing through a black SVU with its doors ajar; inside, they discovered two child car seats, WBZ reported.

“ As a mother, it was incredibly hard, this scene in particular, where there were two children who lost their lives today. ” — Rachael Rollins, district attorney

The garage is the same one where Boston College student Alexander Urtula, 22, died by suicide on his graduation day in May, allegedly at the urging of his girlfriend.

After Wednesday’s incident, Northeastern University said it was blocking off the top floors of the Renaissance Parking Garage.

“The restricted access will continue until a permanent solution is implemented,” it said in a statement. “In addition, effective immediately, there will be 24-hour security staffing in place.”

Rollins, whose office is leading the investigation, noted that the holiday season can be hard for people.

“On Christmas and the holiday season where many people are celebrating, it can be a challenging and difficult time,” Rollins said on Wednesday. “I feel it imperative that we let people know that there is help.”

“As a mother, it was incredibly hard, this scene in particular, where there were two children who lost their lives today,” Rollins added.

Northeastern University did not immediately respond to The Daily Beast’s request for comment, but campus police sent an alert to students about police activity near the Ruggles MBTA station and said they should “avoid the area.”

First responders were offered counseling.

“We know all too well that this kind of trauma leaves scars on first responders as well,” Boston EMS union President Michael MacNeil said, according to WCVB. “We are committed to caring for our members and our brothers and sisters in the police and fire services so that we can all continue to protect the safety and health of the residents and visitors of Boston.”

MacNeil said the woman and children “were given the best possible care we could provide, but it was not enough to save their lives,” MacNeil said. “The thoughts and prayers of the men and women of Boston EMS are with the families experiencing this unspeakable tragedy on this holiday.”

If you or a loved one are struggling with suicidal thoughts, please reach out to the National Suicide Prevention Lifeline at 1-800-273-TALK (8255), or contact the Crisis Text Line by texting TALK to 741741