An officer is on foot chasing a criminal suspect in the dark of night. He's running down Fairfax Street in Alexandria, Virginia and putting out a call for help in his two-way police radio. In another part of the city, Officer Shannon Paul is on patrol in her police cruiser and listening in. She quickly picks up speed and heads to the scene.

"Any fellow officer who's in trouble, you stop what you're doing and you go and you help. Period," she said.

A Night on Patrol With Police in a US City - 2002-07-03

The 34-year old policewoman is on a code three which is a police term for emergency pursuit. She swerves around street corners and comes to a sudden stop at a highway.

A Night on Patrol With Police in a US City - 2002-07-03

"You gotta make sure you don't hit other police officers that are going code three [speeding, siren-blaring cruiser passes], like that."

A Night on Patrol With Police in a US City - 2002-07-03

"What's that mean?"

"That means no more lights and sirens. They got him in custody."

"They stopped a blue car."

"See how many police cars showed up? You have back-up out here. There's plenty of people out here, who are going to be here in a minute if you need help?"

Police officers emerge from about six patrol cars and handcuff the driver they say carried a knife and walked through a neighborhood slashing tires.

Officer Paul seems thin and almost frail talking to the heavyset policemen. This 12-year veteran of the force is tough despite her size. She's a champion at martial arts, carries the standard-issue baton, a 40-calibre handgun in a side holster, and a shotgun in her cruiser. And she likes her dangerous, $30,000 a year job.

"You know I just have this deep sense of justice and that everything needs to be fair and that people who are bad need to go to jail. This is my way, I think, of contributing to society," she said.

A typical night shift may consist of patrolling neighborhoods notorious for drug deals, gang activity, or cases of spouse abuse. She's used to those sort of calls. But every now and then, a call comes over her two-way radio from headquarters that has her worried.

"[call from radio:]?We're getting another call?this is our call"

"So the medics are going and we're gonna go assist and find out what happened."

"Substance. That could be anything."

Right, so we're going to investigate and try to find out what type of assault, if she knows who did it, what the substance is.

"What's your mind going through right now, what are you thinking?"

"I'm a little worried because with the anthrax stuff, I don't want to go in the house without knowing what the substance is."

"Do you have any clothing that protects you?"

We call it our 'weapons of mass destruction gear', we have the face mask, the body suit, the boots, the gloves."

"Where is it, in the trunk or something?"

"It's in the trunk. We're supposed to always keep it with us."

"What about me?"

"You can stay in the car if you want. I don't think I'm going to go on the scene until Hazmat goes on that scene. We're going to find out what's up."

Hazmat stands for Hazardous Materials Unit, a team of rescue personnel that investigates reports of hazardous chemicals. Now, at a cluster of apartment houses, a Hazmat crew searches the room of an elderly woman dressed in a shower cap and bathrobe, the woman who called for help. The Hazmat crew finds nothing. Officer Paul talks to the woman.

"?back into the car. What do you think it was?"

" I think it was her hair rinse. [Maybe] a different batch, different amount. Probably, got in her eyes, and she just got a little panicky. I like it that way. I like it when it ends: everybody's okay. Nobody's hurt."

"Case solved?"

"Case solved."

On the job with Officer Shannon Paul of the Alexandria, Virginia, Police Department.