A Philadelphia police officer died last night after her cruiser collided with a sport-utility vehicle allegedly driven by a drunken teenager in the Mantua section of West Philadelphia.

According to initial reports, the officer and her male partner were trapped inside their vehicle after the two-vehicle crash, which happened about 9 p.m. at 39th and Wallace Streets.

The crash was so severe - the SUV hit the passenger's side of the police vehicle at a high rate of speed - that the side at the point of impact was completely crushed in. The two officers had to be cut out with a Jaws of Life device.

Both officers were transferred to the Hospital of the University of Pennsylvania, where one died of massive head trauma.

Police have identified the dead officer as Isabel Nazario, 40, an 18-year veteran of the force.

Her partner, Terry Tull, 38, a 12-year veteran, is in stable condition.

It is unclear why the officers were chasing the SUV.

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 and was released last night.

The teen is now in police custody with charges pending, police said.

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.

Nazario is survived by her mother, 13-year-old daughter, and a large extended family.

Police said the accident is still under investigation.

Contact staff writer Kia Gregory at 215-854-2601 or kgregory@phillynews.com