PITTSBURGH The public viewing of the flag-draped caskets of three slain Pittsburgh police officers ended this morning, and a procession to a public memorial is being prepared.

The procession will include scores of police cars from other jurisdictions which are now gathering at Heinz Field.

Thousands of mourners, including law enforcement officers, dignitaries and family members, are expected to pack the Petersen Events Center at the University of Pittsburgh for the 1 p.m. memorial service. The arena seats more than 12,000.

The caskets of the slain officers had been on view at the City-County Building downtown since Wednesday afternoon.