Someone was screaming over the police radio.

"Shots fired. Officer down. Give me some help!"

In the quiet of a snowy Thursday afternoon, dozens of officers heard it. In squad cars and on bikes, from the 22d District, the 39th, the Highway Patrol, they rushed to the GameStop at 22d and Lehigh and into chaos.

Inside the store, blood trailed to the door. Broken glass and shell casings littered the floor. And Officer Robert Wilson III was lying a few feet from the counter that shielded a group of shoppers and store workers who crouched down, terrified.

Wilson's partner, Officer Damien Stevenson, stood outside, pointing his gun at a man on the ground.

In a matter of seconds, a routine stop at a local store had turned into a frenzied battle, according to police reports and law enforcement sources. Wilson had held off two gunmen, witnesses later told police. He drew the gunfire away from them as they hid, they said.

And it cost him his life.

Wilson knew some of the workers at the Lehigh Avenue GameStop. One of them told police he was a regular customer. On that day, officials said, he was there to perform a security check and buy a gift for his son.

As his partner waited outside, Wilson chatted with another customer, a 13-year-old girl shopping with her mother, about games for the PlayStation 4.

His son was turning 10 on Monday. He wanted to buy him a gift for his birthday and to celebrate his good grades in school.

According to police records and law enforcement sources, this is what happened next:

As a cashier rang up Wilson's purchase, Carlton Hipps and Ramone Williams pulled on masks, gripped their guns, and walked into the store.

Neither had noticed the waiting patrol car or realized there was a police officer in the store.

Hipps, 29, had spent five years in prison for armed robbery - one that, eerily, had also been interrupted by a police officer, albeit an off-duty one. This time he was accompanied by Williams, 24, his younger brother.

Opening the door, they pulled out their guns.

"Nobody move!" one of them yelled.

When they saw Wilson, witnesses told police, they immediately opened fire - one from the front door, one closer to Wilson.

Store workers and customers dove for cover. The mother of the girl Wilson had been talking to pulled her daughter to the floor.

Wilson was taking fire from both sides at close range, and he was firing back.

The gun battle lasted only 30 seconds. Those inside crouched behind the counter and listened to the shots until there were no more.

The next thing they knew, one of the gunman - later identified as Williams - was slipping behind the counter with them. He hid his gun beneath the register.

"Please, please," he said. "I'm with you all. Don't tell. Don't tell."

Outside, Hipps was on the run, with Stevenson in pursuit. He fired at shot at the officer, and Stevenson fired back and hit him in a leg. By the time backup officers were arriving, Stevenson had Hipps on the ground.

When officers turned him onto his back to pat him down, they saw he had been lying on his gun.

Inside the store, officers securing the scene had three men on the floor - one of them was Williams.

And the shoppers and workers Williams had asked to keep quiet were talking to police. They helped officers uncover his gun and pointed him out from among the three men.

The store manager played security footage for a few officers. It was chilling, but "crystal clear," officials said, and it would prove crucial in the investigation to come.

Williams eventually gave a full confession to homicide detectives, police said. On Friday, he and Hipps were charged with murder and related offenses.

The first officers to arrive at the scene climbed, frantically, through windows and doors shattered by gunfire to reach Wilson.

They found him unconscious, grabbed him by the arms and legs, and hurried his limp body into a police cruiser. An officer from the 39th District rushed him to Temple University Hospital.

Wilson was whisked into surgery. Inside the hospital, his colleagues waited.

The news was not long in coming.

Soon, word spread. Crowds gathered - at the GameStop, at the hospital, onlookers and reporters and camera crews.

Witnesses arrived at the homicide unit. Williams, too. Hipps was taken to Temple Hospital as well and secured to a bed with Officer Wilson's handcuffs.

The police brass held a news conference. From across the city, there was an outpouring of grief. The department set up a memorial fund, and thousands of police officers honored their fallen colleague with black bands on their badges.

And there was this: A crime scene, still active, on Lehigh Avenue. A long procession of squad cars, lights ablaze, stretching down the highway behind the ambulance carrying Officer Robert Wilson III's body to the medical examiner.

And the officers who had rushed him to the hospital, numb in the waiting room, left to face the long night ahead.

215-854-2961 @aubreyjwhelan