Peter Nickeas, a 28-year-old reporter for the Chicago Tribune, describes his experience covering overnight crime on the streets of Chicago.

Standing on Exchange Avenue at 81st Street, looking up at the police helicopter, was the first time I didn't feel like I was in Chicago.

When a helicopter is straight overhead, you can hear it thump. There's a grinding buzz as it approaches, but when it's hovering or moving slowly above, you can hear each rotation.

It was the end of the Fourth of July weekend and Exchange was lit up. Police in green coveralls and black flak jackets patrolled with civilianized rifles made for war. SUVs packed with more firepower were driven into a three-block-by-three-block perimeter.

The air was heavy. Everyone had a glaze over his or her skin. Pants and shirts, duty belts, bulletproof vests. Rifles or handguns. Tasers. Sweaty hairlines.

Soupy air. Mosquitoes. Chicago sits low next to the lake, and overgrown thickets fill vacant lots that dot the South Chicago neighborhood.

Streetlights were out in places and blocked by trees elsewhere. Neighbors walked the sidewalks where the dirty yellow light did not reach, asking what the hell was going on. Officers scanned the ground with LED flashlights, casting a bluish pall as they moved toward the perimeter line.

And with all this weaponry and manpower — enough to take over an airport or maybe even a city center — someone shot up a house two blocks away. The gunfire sent officers scattering, some clutching their belts with one hand as they ran.

I travel to crime scenes; it's what I do. I fly around the city, from point A to point B, getting better at making sense of what I see.

In a little more than two years while working overnight at the Chicago Tribune, I've been to more than 450 scenes. I see cops chasing people, people chasing each other, people fighting each other. I hear gunfire. Sometimes I see it.

But it was the drumbeat of the helicopter and the large-scale manhunt that finally did it for me.

In no more than a minute or two, three people were shot.

Two people walked out of a store on Exchange and someone started shooting. Nothing unique there. The shooter even hit his targets: a 25-year-old man and a 19-year-old woman.

The man was taken to Northwestern Memorial Hospital with a head wound.

"He's dead, but he don't know it yet," a supervisor said at the scene.

He died the next day. The woman was in better shape, with a thigh wound, but also taken to a trauma center.

While the shooter was firing, a couple of other guys started chasing him and trading gunfire with him as they ran from near Exchange toward Escanaba Avenue, a short block west.

They missed each other, but their volley of bullets wounded a 48-year-old man standing on a porch. Another unlucky noncombatant, but lucky enough to have only an ankle wound.

Eight minutes after police arrived, they heard more gunfire and screamed "10-1" into their radios, code for "officer in distress." Someone had fired from a porch a few blocks away while the cops were swarming the neighborhood. Police found only a cluster of shell casings on a porch and took no one into custody.

This scene on Exchange played out during a 13-hour stretch when 30 people were shot in Chicago. The escalation of force from basic patrol to infantry tactics made sense. Standing there, I thought, this all makes sense.

It shouldn't, but that's the way it is. And that's the essence of covering crime in Chicago. Of working overnights. Of covering more than 80 people shot in a holiday weekend. Of living here.