Miriam Carey, a 34-year-old dental hygienist from Stamford, Conn., was believed to be suffering from mental health problems, law enforcement officials told NBC.

A view of the scene with a US Capitol Police car (top) and a black Infinity after a shooting on Capitol Hill October 3, 2013 in Washington, DC. Shots were reported as fired near 2nd Street NW and Constitution Avenue on Capitol Hill. (Photo by Brenden Smialowski/AFP/Getty Images)
Authorities continue to piece together possible motives after a woman was shot and killed by police for attempting to breach the White House security gate Thursday.
Miriam Carey, a 34-year-old dental hygienist from Stamford, Conn., was believed to be suffering from mental health problems when she led police on a 12-block car chase from the White House to Capitol Hill, law enforcement officials told NBC.
According to NBC, investigators gather that Carey may have thought President Barack Obama was stalking her.
The Capitol, caught in a government shutdown, was on edge for the second time in just over two weeks since the deadly shooting rampage that left 12 dead at the nearby Washington, D.C., Navy Yard.
An 18-month-old child, believed to be Carey’s daughter, was in the car during the episode. The girl was taken to the hospital after the scene and was found unharmed. The child is now in protective custody.
New details of the Carey’s personal life are starting to unfold as investigators begin piecing together a possible motive. In an NBC Connecticut interview with Carey’s former employer, Dr. Barry Weiss, a dentist, said that Carey “could be a bit rough” and was fired in August 2012. Months earlier in January, she suffered a fall and missed two to three weeks of work. And according to relatives interviewed by law enforcement officials, Carey suffered postpartum depression.
The car chase began just shortly after 2 p.m. on Thursday when Carey hit a White House security fence with her car. Police were in close pursuit of Carey’s black Infiniti sedan as she raced down Pennsylvania Avenue toward the Capitol, at one point topping speeds of 80 mph. She was later stopped by police and Secret Service at the foot of the Capitol when she bailed from her car. The cops opened fire, and she died a short time later.
Two law enforcement vehicles were struck during the high-speed car chase. A helicopter arrived at the scene to lift away at least one Capitol Police officer to a nearby hospital. The officer was later released Thursday evening.
Witnesses all around the Capitol during the incident described hearing between three and 15 gun shots fired.
NBC’s Pete Williams and Erin McClam contributed reporting to this article.