assault in progress," D.C. police Master Patrolman Alvin Johnson flipped on his siren and flashing lights while his partner, Reserve Sgt. Lloyd Reese, radioed that their squad car was headed for the scene. I was in the back seat on a "citizen's ride-along," my legs squeezed tight and eyes closed as we approached red lights and roared the wrong way down one-way streets.

Coded flashes about a gunman barricaded inside a house in Southeast Washington were periodically bleeped over police band radio, but the task facing Johnson and Reese Friday night was to prevent such a thing from happening across the Anacostia River, in the Northwest neighborhood of Shaw.

Inside a roach- and fly-infested apartment building on 10th Street NW, a man in his forties, dishelved, staggering and reeking of alcohol, stared scornfully at the policemen and expressed his desire for them to leave. But an 11-year-old girl, clinging tightly to Johnson's leg, pointed at the man while her younger brother and sister cried.

"He beat us," she weeped, cutting a fearful glance at a table leg that had been fashioned into a small club. She had a lump on her head. "For no reason," she said.

"I told them to clean up this house," the man slurred. "I'm they stepfather. I been knowed 'em since birth."

I had started out on this ride to find out how street policemen felt about working without a pay raise for the past two years, and having Mayor Marion Barry ignore an arbiter's ruling in their favor. The mayor has suggested that the police officers have been unreasonable and greedy in their new contract demands. Police officers contend that they are entitled to be paid more than other city workers because they put their lives on the line and deal with an extraordinary range of dangerous situations. But on this particular night, there was no griping about pay in the squad car. Instead, the officers were caught up in an unrelenting series of small dramas, each with the potential for erupting into violence and death.

Now here I am in a Shaw apartment, face to face with a man who beats children with belt buckles and table legs, and I feel he deserves a taste of his own medicine. Yet, the stepfather knows that the hands of the police are tied and any direct action on their part may put them behind a legal eight ball.

"You have no right to interfere," he shouted. "And don't touch my stick."

Johnson, a 10-year veteran, and Reese, who has been a volunteer on the police force for nine years, were no strangers to this kind of situation. Here was a man trying to assert his authority, and barricading himself in with his children or even threatening to kill them was not an impossibility, in the light of past police cases.

"Would you please step outside?" Johnson asked politely, which proved to be the first major step toward defusing the conflict that night.

Johnson and Reese had resolved three other domestic disputes that night, but this one -- involving three bruised children -- strained their efforts at sensitivity and fairness.

One of the cases served merely to illustrate the complexity and often utter nonsense that police are up against.

A woman had been found sprawled on the sidewalk with a fist print in her jaw, crying and calling for the arrest of the man who hit her.

"What is his name?" Johnson asked the sobbing woman.

"Well, you really don't expect me to tell the police on the one I love," she replied, then staggered away.

Intervention in domestic disputes is among the leading causes of injuries to police officers, and in each instance Friday night Johnson and Reese had their backup units on hand. But the job of chief domestic mediator inevitably fell to Johnson, 33, a solidly built martial arts student and a marksman with his .38-caliber service revolver.

"Look, sir, there are two ways we can do this," Johnson said sternly to the man who was accused of beating his children. "You can make it easy on yourself or you can make it hard."

As the man pondered Johnson's request for him to leave the apartment, the youngest of the children rolled her sad eyes up at the policeman. "He make us cry," she pouted.

The man rejoined angrily: "Ain't I raised you from a newborn, child?"

Johnson tried to calm him with a gentle hand on the shoulder.

"You kinda violating my rights now," the man snapped. "You touching me and I ain't touching you. You trying to start something?"

"Look, don't you think you may have been drinking too much?" Johnson said to the man. "Why don't we all just go get some fresh air?"

The man's surliness began to dissipate as he walked unsteadily outside, and his voice cracked when he declared, "They are my chil'rens." Tears welled in his eyes as he wondered what he had done wrong. As he agreed to leave the premises, the children's mother showed up, but she wouldn't even talk to the police officers, let alone thank them.

Yet, one child turned and waved goodbye before the door closed in her face.

Johnson said he has learned from experience that confronting men on their home turf inevitably brings out the macho in them, so he practices the "friendly art of persuasion."

In police work, he says, you become aware of emotional booby traps, such as wounded pride from the loss of a job or a failed relationship. The problems often are exacerbated by alcohol, PCP and other drugs. With the odds stacked against them, it takes immense skill and patience on the part of police officers to protect the lives of those endangering themselves and others without breaking the law themselves. Johnson, aided by Reese's voluntary efforts, apparently has mastered that art of street-level diplomacy.

And by the way, he and the rest of the city's cops all deserve a raise.