Both officers were transferred to the Hospital of the University of Pennsylvania, where one died of massive head trauma and the other was listed in critical condition.
The dead officer was identified by police as Isabel Nazario, an 18-year veteran of the force. Her partner's name was not released.
Complete details of the crash were not available early this morning, but initial reports were that the driver of the SUV was an unlicensed teenager who fled after the crash. That driver, described by one official as 16-year-old boy with a record, was arrested after a short foot pursuit.
He was taken to an undisclosed hospital with what was described as non-life-threatening injuries.
When the magnitude of the crash became clear, Commissioner Charles H. Ramsey, police brass and other high-ranking city officials made their way to HUP, and the families of the two officers were summoned.
Also at HUP early this morning was a host of news media waiting for the commissioner to brief reporters with details of what happened. No further information was available.
The Homicide Unit will investigate the accident because it involves the death of an officer in the line of duty.
Last night's death was the second this year involving an officer killed in the line of duty.
On May 3, Sgt. Stephen Liczbinski was killed in Port Richmond while trying to arrest three suspects who had held up a Bank of America branch at gunpoint.
A 12-year veteran and a married father of three, Liczbinski was gunned down days before what would have been his 40th birthday by a desperate suspect wielding a Chinese-made SKS carbine.